Years ago, Sinestro was considered the greatest Green Lantern of the entire Corps and unquestioningly followed the Guardians of the Universe directives, always seeking greater favor from them. Sinestro eventually began to focus ever more on the problems of his home planet and came to the conclusion that with his great power afforded to him by his ring that he could root out all of Korugar's problems and bring the planet to order.
To begin this, he removed the ruling government officials by force and destroyed the capital, shocking and terrifying the populace. Sinestro then moved his family, his wife Arin and his daughter Soranik into a new, more luxurious home. Sinestro failed to realize the affect of his increasingly despotic actions had on his wife, and when he returned home one day, he had found she had hidden their daughter from him and taken her own life.
Consumed by grief over the loss of his family and refusing to believe his wife had killed herself, Sinestro killed all of the remaining former government councilors, believing them to have assassinated her and installed himself as Korugar's ruler. His actions eventually attracted the attention of the Guardians and they sent several of the Green Lanterns corps to investigate, Kilowog and Sinestro's own protege Hal Jordan among them.
Kilowog demanded answers, but confronted and backed into a corner, Sinestro lashed out, attacking all the Lanterns at once with dozens of sword constructs, and so insane at that point he even bit into Kilowog's shoulder. The maddened Lantern was trapped in a net construct formed by several Lanterns and was infuriated as Hal Jordan stripped his mentor of his ring, failing to see Jordan's horror at what he had become.
Sinestro vowed vengeance on all of them, swearing he would tear the Green Lantern Corps apart.
Sinestro along with several of his corps members, capture and ensnare Kyle Rayner on his return to Earth. Sinestro taunts Kyle for his absence from Earth, having watched the events of the past year unfold and proclaims he sees future allies in a coming war. After Kyle mocks him for his appearance, Sinestro moves to remove the young man's Power Ring, darkly asking him "Are you afraid, Green Lantern?"
Kyle attempts to send a warning to his fellow corpsmen but Sinestro brutally rips of Kyle's ring, finger included, and turns his back on the choking human to say, "Now I feel your fear. Powerless, naked, cold and alone in the vacuum of space. There is a war coming," Sinestro promises, just before Kyle is torn to pieces by his captors. "You won't see it." Sinestro says as he looks towards Earth. Sinestro then destroys Kyle's ring to prevent it from finding a new bearer.
Sinestro appears outside the Justice League Watchtower, setting off the proximity alert, observing Superman. The Man of Steel quickly flies out to confront Sinestro, who vainly attempts to hold Superman off, trying to convince him he hasn't come to fight, but Superman slams him into the moon, breaking through or outright ignoring Sinestro's constructs. On the moon, Sinestro manages to choke out to Superman a warning about the Guardians coming, telling him they would "see this world returned to the chaos that was consuming it."
During Superman and Ganthet's meeting in the Hall of Justice, Sinestro speaks to Superman via an earpiece radio, urging the Man of Steel to ask Ganthet "the question". When Superman asks if the Guardians chose to allow Krypton to be destroyed, becoming enraged when Ganthet reveals the Guardians did.
After Superman forces Ganthet to leave, Sinestro comes out of hiding, telling Superman that he now realizes the same thing he did so long ago, that the Guardians are in 'name only'. Sinestro apologizes for Krypton's fate, but Superman makes it clear he doesn't trust Sinestro. Sinestro says that doesn't matter, but knows the Guardians will come for Superman, and he knows the Man of Steel will need him when they do.
Sinestro is locked in a special cell inside the Hall of Justice, observing the argument between Superman, Flash and Lex Luthor as the two try to convince him of the dangers of keeping him around. Sinestro agrees with the two that he is dangerous, and tells him that his 'pets' are wise to fear him but Sinestro tells the Man of Steel that they are the same. The Flash objects to this, calling Sinestro a monster, but Sinestro tells him he is not, that it is simply easier to think of him as a monster and once more insists that he and Superman are the same.
Sinestro explains that the reason he has come to Earth is because he sees much of himself in Superman and that was why he told him of the Guardians and their role in Krypton's destruction and that he sees Superman suffering from similar pains as he once did.
Sinestro then relates his origins to Superman, though he lies or omits many parts, casting himself in a more sympathetic light, before ultimately lamenting the 'betrayal' of his student Hal Jordan, and once more tells Superman that the Guardians are coming. Neither the Flash or Luthor are won over, but Superman greatly sympathizes with Sinestro.
Lex insists that they cannot trust him and the alien warlord agrees, but Sinestro says that he has no interest in the Earth's destruction and that he only wants revenge on the Guardians and needs Superman to stand with him against them. Flash says they should leave Sinestro in his cell to rot, but Sinestro suddenly begins glowing with the golden light of fear, mockingly asking, "You think you can contain me?"
He then easily walks through the energy door and out of his cell, which shocks Luthor, who proclaims it impossible as nothing could escape it. Sinestro only tells him that he has no idea what he is capable of, with Luthor agreeing. When Sinestro threatens to kill him with a thought, the Flash moves between them, retorting that he'll beat him down faster.
Stating, "You fear me," with Luthor agreeing, Sinestro decides that there is only one way to earn their trust and removes his ring, giving them "their fear" and removing himself of his powers. Sinestro once more tells them that the Guardians are in name only and that they only want control and asks how many more planets and civilizations will they watch burn and how many more times they will choose death over life. As he turns back towards his cell, he admits he is not a good man anymore but says that Superman will need him when the time comes and that together they will end the Guardians.
Sinestro is still imprisoned in the Hall of Justice, being observed by Lex Luthor and Hawkgirl. Though Luthor is convinced Sinestro has another plan, Sinestro merely repeats that the Green Lanterns will soon arrive, and they will return his ring and power to him so that he and Superman can work together to defeat them.
Sinestro realizes that the Green Lantern Corps have arrived on Earth, and tells Luthor that Superman will need his help. When Lex makes it clear he won't let Sinestro out of his cell, Sinestro grins and says, "Now I see it." When Lex asks what he sees, Sinestro replies, "The ambition."
Sinestro then stats that Luthor wants Superman to fail, before asking him if he wants the world for himself. Luthor warns him to watch his words, but Sinestro only tells him that when the Corp comes for Superman, his dream for this world will die, and only he can stop them. But Sinestro then asks, "Unless you don't want me to...?"
Luthor then reluctantly frees Sinestro from his cell and hands his ring back over to him, but not before telling Sinestro that he won't let him corrupt Kal-El. Sinestro takes back his ring and tells Lex, "He doesn't need me to."
Later, just as the Green Lanterns have successfully subdued Superman and his allies Shazam and Hawkgirl, Sinestro arrives and kills Ch'p, who was keeping Superman incapacitated. Kilowog sees Sinestro and can only stare in shock at both his sudden appearance and murder of Ch'p. Sinestro simply mocks Kilowog as he says, "Oh, don't look at me like that, "poozer." I did you all a favor. You always looked ridiculous fighting beside a squirrel."
While Superman and his allies battle Kilowog and the other Green Lanterns, Sinestro single-handedly engages over half a dozen of Kilowog's squad-mates, repelling them with sword and other bladed weapon constructs. Though the recently arrived John Stewart and Hal Jordan attempt to stop the fighting, Sinestro reveals that several dozen of his Corps members have arrived on Earth. Though Sinestro assures that his Corps aren't against him, Superman demands to know what is going on, Sinestro replies, "This is how you win a war."
Kilowog admits defeat and requests that he and his squad be allowed to return to Oa but Sinestro refuses. His former protege Hal Jordan claims that the decision is not his to make but Sinestro ignores him and tells Superman that they can't allowed to return to Oa, saying that they will only return with the rest of the Green Lantern Corps. Superman reluctantly agrees and as Sinestro's Corps surround the Green Lanterns, the warlord tells him, "You know what must happen. They must be exterminated."
Sinestro's Corps have captured Kilowog and his squad of Green Lanterns, keeping their hands bound with yellow shackle constructs. Sinestro is trying to convince Superman to let them exterminate the Lanterns less they return to Oa and bring the rest of the Corps to challenge his rule, though Sinestro's former protege Hal Jordan vehemently refuses to allow this. Sinestro tries to talk to Superman, though Shazam insists they won't condone any executions.
When Arkillo begins torturing Kilowog for speaking out of line, both Hal and Superman order him to stop, and Sinestro eventually commands Arkillo to cease. Looking to Superman, Sinestro tells him, "If you won't kill them, then realize that this is war. There are prisoners in war." Superman agrees and orders the Green Lanterns to remove their rings.
Though reluctant and angry, the Green Lanterns agree and surrender themselves. Superman then tells Sinestro his Corps are not welcome on Earth and he wants them gone. Sinestro attempts to protest but John Stewart and Hal Jordan tell him and his Corps to leave, though Superman says that Sinestro will stay, as he owes him for saving him from being captured by the Green Lanterns. Sinestro then orders Arkillo to take the Corps and leave Earth but to remain ready, having already hidden themselves from the Guardians but that the war is just beginning.
Sinestro is summoned alongside his former protege Hal Jordan by Superman, with the Man of Steel revealing to them that the Guardians of the Universe have located the Ur-Forge of the Weaponers of Qward. Sinestro expresses his doubts over the forge's existence, stating that many Lanterns believe it to only be a myth, though Superman not only confirms its existence but its current location. When Superman tells the two that the Guardians are hunting for the forge, Sinestro quickly realizes that the Ur-Forge could unleash "unimaginable" dangers upon the Earth.
Superman wants Hal and Sinestro to bring him the forge for the sake of the planet and its people, hoping that Sinestro's knowledge of the Weaponers and Hal's knowledge oft he Guardians will allow them to effectively recover it.
With that, teacher and student depart into the deepest recesses of space, flying to the planet where the Ur-Forge is located, the planet itself a moon where the Weaponers left their first creations. Sinestro quickly realizes that the moon is also, "the evolutionary cesspool from which the Weaponers crept." and that the Weaponers completely stripped their birthworld of its original aspects and replace them with their own creations, believing them superior.
Sinestro and Hal are attacked by a mechanical monstrosity, one of the Weaponers creations, and while Sinestro tries to defend his former student, Hal quickly destroys the monster himself while warning Sinestro to back off. Sinestro is astonished that Hal no longer trusts him, citing all they've been through, although Hal only uses that as validation for his mistrust.
Later the two rest by a fire, deciding to continue searching for the Ur-Forge in the morning. Sinestro offers to take watch but Hal quickly rebuffs his offer. Sinestro tells Hal, "You don't trust me. You don't need to. You trust him."
Hal says that Superman is his friend, and Sinestro asks asks what happened to their friendship and how they fell so far that they now long to hack and slash at each other like civilized killers. Hal snaps that Lanterns aren't killers and Sinestro retorts, "So it was said of Superman."
Sinestro tells his former protege that he has seen this all before, that he has seen worlds die because one man thought himself a savior and admits that he was that man and he brought devastation to his home world of Korugar, before reminding Hal that he was his friend once. Sinestro goes on, saying, "When you see Kal...it is me you truly see. Me, when you failed to stop me. Me, given a second chance. And this time you might save so many lives."
Hal is silent, and so Sinestro turns around, joking about who will make breakfast in the morning, with Hal retorting that a sense of humor comes with the genocidal starter kit. Sinestro just reminds him that he has seen many worlds die and that gallows humor awaits them all at the end. The two do not have long to rest before they are attacked by another mechanical monster, this one larger and more powerful than the first.
Sinestro quickly picks up the Ur-Forges signal and is horrified to discover that it has moved. Sinestro and Hal fly ahead of the monster, with Sinestro creating several rammed horned constructs to attack the creature to keep it baited and following them. Sinestro and Hal then find the Ur-Forge being carried away by several Green Lanterns. Sinestro unleashes the monster on the Lanterns, allowing him and Hal to steal the Ur-Forge in the confusion.
After successfully escaping the Lanterns, Hal and Sienstro stop for a moment to look over the forge. Sinestro carefully studies the massive weapon before his eyes widen. With a single blast from his ring, Sinestro destroys the Ur-Forge, preventing it from falling in either the Guardians or Superman's hands, ensuring it will never be used again.
A shocked Hal quickly realizes what Sinestro has done, and the teacher smiles at his former student, asking, "You were worried, weren't you? That little tang of not-quite-fear...Were you more afraid of what the Ur-Forge would do in the Guardians' hands, Superman's..or mine?"
Hal asks how he could be afraid when he knew Sinestro was the one at his back as the friends clasp hands.
Later, Sinestro and Hal return to Earth, where Hal explains to Superman that the forge was destroyed before they could recover it. Superman believes that to be for the best before thanking both of his allies, saying that the forge didn't fall into the wrong hands before flying away. Sinestro shares a smile with Hal before agreeing, "No...No, it did not."
Seven months later, Sinestro has been on Earth and slowly re-earning Hal Jordan's trust by helping Superman and the Justice League spread their influence over the Earth. To further gain Hal's trust, Sinestro has his Corps attack Despero and throw him down to the Earth, his impact straight for Chicago. Sinestro 'intervenes' as Despero crashes down through a multi-story building and he plays the part of the hero by 'demanding' to know why Despero is attacking, as well as expressing his 'outrage' for endangering innocent people.
Despero is not amused and demands answers from Sinestro, but Sinestro only continues to act like Despero is truly attacking, and tackles him outside just as Hal Jordan and John Stewart arrive. Sinestro then uses his ring on a confused Despero to take control of his hands, forcing Desperso to strangle him. Sinestro then forms a bubble construct over Despero's neck and while 'pleading' with the alien tyrant to stand down, he ultimately snaps his neck right in front of Hal and John.
Feigning sadness over being 'forced' to kill Despero, Sinestro apologizes to Hal, who easily forgives him and Sinestro flies off, claiming they need to help the people in the building Despero crashed in. Sinestro grins to himself as he over hears Hal discussing with John on how he believes Sinestro has truly changed and begun to redeem himself.
Sinestro is alerted by two of his Corps members of the approach of a massive gathering of Green Lanterns heading for Earth. Sinestro is then seen at Superman's side as the Man of Steel makes an announcement to the people of the Earth, revealing the imminent arrival and war with the Green Lanterns Corps. Sinestro is completely silent as Superman implores the common people to work with them in repelling the Green Lanterns. Past news broadcasts during this reveal Sinestro worked with the Justice League in toppling 'rogue nations' to help expand Superman's sphere of influence across the planet.
Sinestro joins Superman and his Corps in confronting the recently arrived Green Lanterns. When the war begins, Sinestro is caught in a blast fired by Mogo. Sinestro survived while over a quarter of his Corps were wiped out, saved by Superman along with his protege Hal Jordan.
Sinestro is fighting alongside his Corps against the Green Lanterns when he sees both Hal Jordan and Guy Gardner fly down to Earth. Sinestro follows after them, accompanied by two of his Corpsmen, and when he finds Hal and Guy arguing at Ferris Aircraft, he blasts Guy with a burst of yellow energy. When Guy begins telling Hal how he was supposed to better than joining with Sinestro and Superman, Sinestro orders his Corps to shut Guy up and to end him.
Guy is saved by Ganthet's intervention and Sinestro finds himself blasted back by the all-powerful immortal. Enraged at both being attacked and by the mere sight of a Guardian, Sinestro picks up a nearby plane with his ring and chucks it at Ganthet, though it only serves to annoy the immortal at best and is easily destroyed. When Ganthet then strips Hal of his powers by taking back his power ring, Sinestro strikes Ganthet with a hammer construct, ordering him to let Hal go.
When his falling protege calls to him, Sinestro flies over, but when Hal pleads with him to save Carol, Sinestro responds, "No." Telling Hal, "We need you in this war," Sinestro smiles with sinister delight as he presents Hal with a yellow power ring and tells him, "Save her yourself."
When Hal hesitates, Sinestro tells him, "This isn't a moral quandary! You're powerless, Jordan. Carol will die. Take it. Save her." Hal then claims the ring, and Sinestro guides him in using it, telling him, "Now--feel her fear. Use it!" This allows Hal to form a large hand construct to save Carol from falling to her death.
As Hal floats in the air empowered with the yellow light of fear and now wearing a Sinestro Corps version of his uniform, Sinestro can barely contain his glee at having regained his protege, and he says, "They tried to cast you aside. They tried to take her from you. They tore us apart, but they forced us together again, Hal. You and I. We are one Corps again. Let us show them fear."
Sinestro observes with a twisted look of pride on his face as he watches Hal harness Carol's fear to empower his ring and save her. When Ganthet declares Hal has fallen, Sinestro moves in front of the Guardian in defense of his protege, proclaiming that Hal has found a truer path, while calling Ganthet self-righteous. When Ganthet says that Sinestro was never good enough for the Green Lantern Corps, Sinestro counters and exclaims, "We are better than your Corps!"
Ganthet tells Sinestro that pride was always his undoing (With Guy Gardner adding that his countless murdering of innocents didn't help) before declaring that both he and Hal were mistakes.
When Ganthet turns his back on Sinestro and prepares to leave with Guy Gardner, Sinestro demands to know where he is going. When Ganthet responds that he is leaving to deal with someone more important than Sinestro, the warlord snaps at being so abruptly dismissed and charges at Ganthet with his Corpsmen flanking him, his true selfish personality briefly coming out as he roars, "THERE IS NO ONE MORE IMPORTANT THAN ME!!"
Ganthet then easily kills Sinestro's soldiers, with Sinestro himself only barely managing to save himself with a shield construct that almost shatters from the force of Ganthet's power. Ganthet then declares that Sinestro is utterly insignificant before flying off, leaving Sinestro to watch as one of his sworn enemies escape's his grasp.
Sinestro appears on the battlefield between the Corps, calling out to John Stewart as the Green Lantern unsuccessfully tries to stop the fighting between the forces of Willpower and Fear. Sinestro demands to know what John is doing before telling him that he can't stop this war. "The Guardians don't care about your world. Superman does. We need you on our side." Sinestro tells John.
Sinestro tells John, "Stop reacting. Close your eyes and think." Placing his hand on John's back, Sinestro reminds John that he is an architect and to, "See the design. See what the Guardians have planned for your world. See how they want this universe built around them."
Sinestro asks John, "Can you see it?" John replies that he doesn't want to. With a grin, Sinestro responds, "I know--" while forming a blade to stab John straight through his chest from his ring hand against John's back. "The truth is painful." Sinestro tells John with a triumphant grin.
A horrified and dying John looks up at Sinestro, who 'consoles' him by saying, "It's all right, John Stewart. You will help us after all." He then dissipates his construct and carries Stewart's dying body over to Hal Jordan.
Acting panicked, Sinestro orders a shocked Hal to get John medical attention, though Stewart dies in Hal's arms moments later. When an enraged and grieving Hal demands to know who killed his friend, Sinestro 'painfully' reveals that the murderer to have been Guy Gardner, claiming Guy killed an unsuspecting John while Stewart was trying to stem the loss of life on both sides. As Hal glares in fury at a nearby Guy Gardner, Sinestro tells him, "You know, don't you? Gardner always felt unworthy. He was only your replacement. You know he always wanted to be the only one. The only Green Lantern of this sector."
Taking John's body from Hal, Sinestro 'consoles' his student, "I know it hurts to hear but I believe he wanted this. He brought this war here. He planned all of this."
This proves to be the final straw for Hal, and Sinestro watches with delight as Jordan attacks Guy, who refuses to fight back against his friend. Disposing of John's body, Sinestro goads Hal on when Jordan gets Guy by the collar. "Kill him, Jordan!" Sinestro orders.
Guy tries to tell Hal not to listen, but Sinestro continues. "He will take what is yours. Your world. Your loved ones." Guy desperately tries to convince Hal that the ring is affecting his mind and that he can still be the best of all of them.
But Sinestro's manipulations triumph, and Hal rips off Guy's broken arm before allowing him to fall to his death. Sinestro succeeds in not only putting Hal in his Corps but committing his first murder as well, completely trapping Jordan in his thrall.
With the Green Lantern Corps utterly devastated, and only Ganthet and Mogo remain. Sinestro joins with Hal Jordan at Superman's side as the three ring bearers of Fear confront the last standing bearer of Willpower. After Ganthet reveals he is no longer interested in bringing Superman back to Oa for trial and declares him a threat to all worlds beyond the Earth. Sinestro and Hal are forced to shield themselves from Ganthet's attack, but Superman is unaffected, having been further empowered by the fear of over a billion people on Earth.
As Ganthet's power fades, Superman snatches the immortal by the neck and a recovering Sinestro tells him, "He tried to execute you, Superman." Superman agrees and in a stunning and awe-inspiring display of his new-found power, destroys Mogo and kills Ganthet both simultaneously by plunging them into the sun. Sinestro and Hal Jordan watch the execution from space, surrounded by the bodies of both Green Lanterns and Sinestro Corps members.
When Hal asks his mentor what they have done, Sinestro tells him: "What we set out to do. We saved the world." This was Sinestro's ultimate victory, the warlord having used Superman to regain Hal as his student, wipe out the majority of the Green Lantern Corps and kill a Guardian of the Universe.
Sinestro floats outside the ruined Hall of Justice while Hal tells him that Flash, Cyborg and Robin are all gone, with Sinestro asking where. Superman touches down behind them and explains Batman's forces were able to take them before vanishing. When Sinestro asks, "How can they vanish from your senses? How can our rings detect nothing?" Superman responds that magic is the culprit.
Sinestro brings Officer Sprague before Superman at the Hall of Justice. When Sprague doesn't respond to Kal-El's greeting, Sinestro forms a large hand construct around the man's neck and lower jaw, barking, "Answer him!" though Superman is quick to calm Sinestro down. After Superman subtly threatens Prague's wife, the officer admits he doesn't know where their missing allies are, promising that he's telling the truth. A smirking Sinestro responds, "We will see."
Sinestro tortures officer Sprague, using his ring to form electrified shackles and various probes to make the process as painful as possible. Sinestro compliments Sprague for the amount of punishment he's endured and maintaining his silence. Superman tells Sinestro's that he's done enough, but a sadistically smirking Sinestro replies, "Not yet." while upping the charge of his ring to increase Sprague's pain.
Superman cuts Sinestro's ring off and tries to pull Sprague to his feet. Exasperated, Sinestro snaps, "No! No kindness!" before grasping the Man of Steel by his shoulder and guiding him outside the cell for a word. Sinestro tells Superman that he understands if he's not comfortable with Sinestro's 'enhanced interrogation' but reminds him that their allies are being held and they have no idea what their enemy is doing to them.
Superman is convinced that Sprague knows nothing but Sinestro reminds him that Batman is capable of inspiring loyalty in his followers. A torn Superman hesitates and Sinestro comforts him, "Part of leadership is knowing when to delegate to the strengths of others. This is unpleasant business but it's something I'm very effective at."
Swearing that if Sprague has information he will find it, Sinestro reminds Superman that he has other duties, such as protecting and nurturing his world and that he is far too important to concern himself with one traitor. Asking Superman to let him take this 'burden', Sinestro resumes torturing Sprague when Superman agrees.
Moments later however, Sinestro is quick to return to Superman's side when a loud voice booms through the Hall of Justice, calling to the Man of Steel. Superman orders Sinestro to put his ring away, telling him it is useless against this. Sinestro joins Superman in confronting the Spectre outside, flying beside Shazam as the Spirit of Vengeance relays his message and intentions to join them.
Sinestro is seen in the Hall of Justice alongside Yellow Lantern, Lex Luthor and Shazam when the Spectre alerts them that Superman is missing. When Superman manages to activate his com-link and alert them to his location in Gotham, Sinestro accompanies Hal and the Spectre to Gotham to confront Superman's attacker, John Constantine.