Zero Hour

Background

Zero Hour was presented by DC as a follow-up to their landmark "maxi-series" Crisis on Infinite Earths, and subtitled "Crisis in Time". It promised to do for the inconsistent future timelines of the DC Universe what Crisis had done for its parallel worlds: unify them into a new one.

The event served as an opportunity to reconcile some of the problems left unaddressed by Crisis, or 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, some of them a year or several after the first ones. The character of Hawkman was one of the most problematic, as a revised version was not introduced until 1989, raising the question of who this old-version "Hawkman" character was that had been running around with the post-Crisis heroes since 1986. (He had been retconned to be both the Golden Age Hawkman and a Thanagarian spy.) The Legion of Super-Heroes faced similar problems with the elimination of Superboy from DC continuity. (Valor, a character with similar powers, had been recast to take his place as the Legion's inspiration and most powerful member.) These and other retcons were not always well-received by readers, and often introduced new problems.

Story

The event was introduced by the apparent destruction of the DC Universe in the monthly issues of every DCU series published that month. Near the end of each issue, the world began to disappear, and the last page of the book (or in some cases, several pages) were blank. Meanwhile, the plot causing the cataclysm unfolded in the series itself.

The apparent villain of the story was a character named Extant, who was using his temporal powers to unravel the DC Universe's timeline. In a confrontation with members of the Justice Society of America, Extant aged several of them (removing the effect that had kept these heroes of the 1940s vital into the 1990s), leaving them either feeble or dead. The true power behind the destruction of the universe turned out to be former Green Lantern Hal Jordan, now calling himself "Parallax". Jordan had previously gone insane, and was now trying to remake the universe, undoing the events which had caused his breakdown and his own murderous actions following it. The collective efforts of the other superheroes stopped Parallax from imposing his vision of a new universe, but the universe the heroes recreated was not identical to the previous one.

Outcome

DC published a timeline at the end of Zero Hour #0 which identified various events and key stories which were part of its newly singular timeline, and when they occurred. Although fixed dates were given for the debut of historical characters such as the JSA, the debut of the post-Crisis Superman was presented as "10 years ago" and subsequent dates were expressed the same way, suggesting that the calendar years of these events were fluid and relative to the present rather than fixed, as a way to keep the characters at roughly their present ages.

The Legion of Super-Heroes was completely rebooted following Zero Hour, and the various Hawkman characters were merged into one. Each ongoing series at the time was given an opportunity to retell the origin of its hero to establish the official version in this revised continuity, in a "#0" issue published the month after Zero Hour. They resumed their previous numbering (or went on to #1, for new series) the month after that. Several series took new directions following Zero Hour; for example, a new team formed in Justice League America, Oliver Queen's son Connor Hawke was introduced in Green Arrow, and Guy "Warrior" Gardner discovered an alien heritage which gave him different powers.

But this "warm reboot" did not solve all continuity matters ("Who is Hawkman?" actually became less clear), and some fans and creators feel that multiple worlds and timelines were an asset rather than a hindrance to the DC Universe. For those and other reasons, DC later introduced a variation of the pre-Crisis concept of the Multiverse, in the form of Hypertime. Hypertime, however, has been infrequently utilized in DC titles, perhaps as a result of its chief architects and proponents, writers Mark Waid and Grant Morrison, not doing much work for DC in the years following its introduction in 1998's The Kingdom.

Zero Hour also served to launch or end several ongoing series. A few of these were dictated by the changes in continuity that came out of the story, but most happened simply because it provided a convenient marketing opportunity to start new series.

Series ending with Zero Hour