"Zero Hour: Crisis in Time!" is a comic book crossover storyline published by DC Comics in 1994, consisting of an eponymous five-issue limited series and a number of tie-in books. In the storyline, Hal Jordan, a member of the intergalactic police force known as the Green Lantern Corps, goes mad with grief after the destruction of his home town of Coast City during the "Reign of the Supermen!" storyline and attempts to destroy and remake the DC Universe after having obtained immense power as Parallax. The issues of the limited series were numbered in reverse order, beginning with issue #4 and ending with #0. The crossover involved almost every DC Universe monthly series published at the time. Background Zero Hour: Crisis in Time! was the follow-up to the Crisis on Infinite Earths limited series. This event served as an opportunity to reconcile continuity problems left unaddressed by Crisis and other problems that had been unintentionally caused by it. In particular, the revised characters of the post-Crisis universe had been rolled out gradually, with DC continuing to feature the old versions until the new versions were launched. Plot The story begins when characters from alternate realities such as Alpha Centurion, an alternate version of Batgirl, and Triumph suddenly start appearing in the DC Universe. A wave of entropy then moves from the end of time to the beginning, erasing entire historical ages in the process. The villain of the story is Extant, formerly Hawk of the duo Hawk and Dove. Extant has acquired temporal powers, using them to unravel the DC Universe's timeline. In a confrontation with the Justice Society of America, Extant ages several of them — removing the effect that has kept them young from the 1940s into the present day — leaving them either feeble or dead. However, the true villain behind the destruction of the universe turns out to be Hal Jordan, a member of the Green Lantern Corps. Calling himself Parallax, Jordan has gone insane and is now trying to remake the universe, undoing the events which have caused his breakdown and his own murderous actions following it. The collective efforts of the other superheroes manage to stop Parallax from creating his vision of a new universe, and the timeline is recreated anew, albeit with subtle differences compared to the previous one, after the young hero Damage, with help from the other heroes, triggers a new