Starting his professional writing career at Marvel Comics, Casey wrote for several titles, including Cable, The Incredible Hulk and Uncanny X-Men.

Since 2001 Casey has produced creator-owned work through Image Comics, including Gødland, Codeflesh, Nixon's Pals, Charlatan Ball, Doc Bizarre, M.D., Officer Downe.

[4] Casey is a member of the Man of Action collective of creators (with Joe Kelly, Duncan Rouleau, Steven T. Seagle), who created the series Ben 10, airing on Cartoon Network.

Dark Reign: Zodiac pits a new iteration of the old Avengers enemies against Norman Osborn's new status quo as Director of National Security,[5][6][7] and Final Crisis: Aftermath: Dance follows the adventures of the Super Young Team.

Huddleston responded to Casey's public statement by stating that the delay was caused by his need to take over work in order to make sufficient money, as Butcher Baker was not lucrative enough for him to avoid doing so.