Production
Kevin Conroy reprised his voice role as Batman from Batman: The Animated Series (1992–1995), The New Batman Adventures (1997–1999), and Batman Beyond (1999–2001). Batman's costume was redesigned, but this time, his costume was a combination of his last three costumes. The same costume from The New Batman Adventures is retained, but with the blue highlights from the Batman: The Animated Series costume and the long-ears from the Batman Beyond costume are added to the costume. Tim Daly, who voiced Superman in Superman: The Animated Series (1996–2000), was initially involved, but was unable to reprise his role due to involvement with The Fugitive. He was replaced by George Newbern. Both Newbern and Daly have voiced the character in different DC projects outside the DCAU, with Newbern becoming the longest-running actor to portray Superman.
Alongside Kevin Conroy and George Newbern as Superman, joining the rest of the main cast is Susan Eisenberg as Wonder Woman, Maria Canals-Barrera as Hawkgirl, Phil LaMarr as John Stewart, Michael Rosenbaum replacing Charlie Schlatter as the Flash, and Carl Lumbly as J'onn J'onzz.
Several actors in previous DCAU media also reprise their roles, including Dana Delany as Lois Lane, David Kaufman as Jimmy Olsen, Efrem Zimbalist Jr. as Alfred Pennyworth, Shelley Fabares and Mike Farrell as Jonathan and Martha Kent, Mark Hamill as the Joker, Clancy Brown as Lex Luthor, Corey Burton as Brainiac, Ron Perlman as Clayface, Arleen Sorkin as Harley Quinn, Peri Gilpin as Volcana, Diane Pershing as Poison Ivy, Mark Rolston as Firefly, Ted Levine as Sinestro, Brian George as Parasite, Michael Ironside as Darkseid, Michael Dorn as Kalibak, Lisa Edelstein as Mercy Graves, and Brad Garrett as Lobo. In the episode "Hereafter", Maria Canals-Barrera voiced Livewire and Corey Burton voiced Toyman and Metallo, replacing their respective original actors Lori Petty, Bud Cort, and Malcolm McDowell.
