scale) with 1994's Zero Hour crossover storyline. In the late 1990s, the concept of Hypertime was introduced as an attempt to satisfy fans of alternate realities, by stating that all comics published by DC (whether pre- or post-Crisis) had taken place in some corner of reality. In 2005, the Infinite Crisis series revived the idea of a multiverse. Following the events of the Infinite Crisis series, Superman, Batman and Wonder Woman have temporarily retired their costumed identities. The remaining heroes attend a memorial for Superboy in Metropolis. Time traveler Booster Gold attends the memorial, but when Superman, Batman, and Wonder Woman do not arrive, the change in history makes his robot sidekick Skeets malfunction. This results in Skeets reporting other incorrect historical data. Booster and Skeets search time traveler Rip Hunter's desert bunker for answers, but find it littered with scrawled notes (See "Rip Hunter's lab" below). The series continues, exploring many of the changes wrought by the events of Infinite Crisis, introducing new characters, killing off old ones, and putting others in new situations. The series concludes when Rip Hunter reveals that a new multiverse exists, of exactly 52 universes, from Earth-0/New Earth (The primary Earth in continuity) to Earth-51. The new Multiverse is temporarily threatened by Mr. Mind, who has developed the ability to travel to each universe and "Eat" portions of it, altering its history. Each new universe was initially identical to New Earth, but Mr. Minds rampage altered each universes history, altering them all, returning the D.C. Multiverse after a fashion. Once Mr. Mind is stopped, and 52's World War 3 crossover concludes, it is revealed that new Monitors exist for each of the new universes, making 52 monitors in all. Many of the new universes resemble either popular Elseworlds Earths (Kingdom Come, Batman and Dracula) or are similar to the pre-Crisis Earths 2, X, S, etc. 52, World War 3, 1 Year Later, and Crisis Aftermath indirectly lead into Countdown, which is confirmed to be counting down to the next big event, Final Crisis. Watchmen In 1986, DC published two groundbreaking limited series: Watchmen by a British creative team led by writer Alan Moore and artist Dave Gibbons and Batman: The Dark Knight Returns by Frank Miller. The Watchmen helped usher in the era of anti-heroes. But, more importantly, it was one of the most artistically ambitious and psychologically complex comic book series ever produced.