first major project for Marvel Comics was as one of the writers of the "Age of Apocalypse" crossover. He later co-created the Onslaught character for the X-Men line. Marvel editors Ralph Macchio and Mark Gruenwald hired him as Gruenwald's successor as writer of Captain America, during which Waid was paired with artist Ron Garney. Waid and Garney garnered critical praise for their run on the title, remaining on it until the title was relaunched with a different creative team as part of the 1996–1997 "Heroes Reborn" storyline. Rob Liefeld offered Waid the opportunity to script Captain America over plots and artwork by his studio, but Waid declined. That storyline ran a full year, after which Waid and Garney returned to the title for another relaunched series, Captain America volume 3, issues #1–23. Waid also wrote the short-lived spin-off series Captain America: Sentinel of Liberty from 1998 to 1999, having written 10 of the 12 issues (skipping issues #7 and 10). In 1996, Waid and artist Alex Ross produced the graphic novel Kingdom Come. This story, set in the future of the DC Universe, depicted the fate of Superman, Batman, Wonder Woman, and other heroes as the world around them changed. It was written in reaction to the "grim and gritty" comics of the 1980s and 1990s. DC Comics writer and executive Paul Levitz observed that "Waid's deep knowledge of the heroes' pasts served them well, and Ross' unique painted art style made a powerful statement about the reality of the world they built." Many of the ideas introduced in Kingdom Come were later integrated into the present-day DC Universe, and Waid himself wrote a follow-up to the series, The Kingdom. Waid and writer Grant Morrison collaborated on a number of projects that would successfully reestablish DC's Justice League to prominence. Waid's contributions included JLA: Year One, as well as work on the ongoing series. The two writers developed the concept of Hypertime to explain problems with continuity in the DC Universe, which was first introduced in The Kingdom. 2000s Waid collaborated with artists Bryan Hitch and Paul Neary on JLA and the JLA: Heaven's Ladder (Oct. 2000) one-shot. In 2000, Waid co-wrote a series named Empire with Barry Kitson, whose protagonist was a Doctor Doom-like supervillain named Golgoth who had defeated all superheroes and conquered the world. The series was originally published by Gorilla Comics, a company formed by Waid,