The Justice League
Tom Welling - Clark Kent/Superman
Christian Bale- Bruce Wayne/Batman
Adrianne Palicki - Princess Diana/Wonder Woman
Ryan Reynolds - Hal Jordan/Green Lantern
Justin Hartley - Oliver Queen/Green Arrow
Lee Thompson Young - Victor Stone/Cyborg
Alan Ritchson - Arthur "AC" Curry/Aquaman
Kyle Gallner - Bart Allen/Impulse
Alaina Huffman - Dinah Lance/Black Canary
Eric Martsolf - Michael Jon Carter/Booster Gold
Jaren Brandt Bartlett - Jamie Reyes/Blue Beetle
Phil Morris - John Jones/Martian Manhunter
Fred Tatasciore (voice only) - Darkseid: The main antagonist of the series who is revealed to have survived the final events of Smallville. In Justice, his appearence will be more similar to his comic book counterpart and he will be able to physically battle with the Justice League.
Callum Blue - Major Zod: Darkseid's newest follower. After the death of his three minion prophets Granny Goodness, Godfrey and Desaad, Darkseid needed a new minion, so he freed Zod from the Phantom Zone and recruited him.
The Injustice League
Jackie Earle Haley - Joker: Batman's arch nemesis, he founded the new Injustice League to finally destroy Batman.
John DiMaggio (voice only) - Gorilla Grodd
Gina Torres - Cheetah
Mark Strong - Sinestro
Cllian Murphy - Scarecrow
Dwayne Johnson - Black Adam
Tim Roth - Killer Croc
John DeSantis - Solomon Grundy