Kara, devastated by the loss of Krypton, struggles to adjust to her new life on Earth. Her cousin, Superman, mentors her and suggests she leave their space-time to attend the Legion Academy in the 31st century, where she makes new friends and a new enemy: Brainiac 5. Meanwhile, she must contend with a mysterious group called the Dark Circle as it searches for a powerful weapon held in the Academy’s vault.
| Actor | Role |
|---|---|
 Meg DonnellySupergirl / Kara (voice) | Supergirl / Kara (voice) |
 Harry Shum Jr.Brainiac 5 (voice) | Brainiac 5 (voice) |
 Jensen AcklesBatman (voice) | Batman (voice) |
 Gideon AdlonPhantom Girl (voice) | Phantom Girl (voice) |
 Matt BomerThe Flash (voice) | The Flash (voice) |
 Darren CrissSuperman (voice) | Superman (voice) |
 Robbie DaymondTimberWolf / Brainiac 4 (voice) | TimberWolf / Brainiac 4 (voice) |
 Darin De PaulBrainiac / Solomon Grundy (voice) | Brainiac / Solomon Grundy (voice) |
 Ben DiskinArms Fall Off Boy / Brainiac 2 (voice) | Arms Fall Off Boy / Brainiac 2 (voice) |
 Victoria GraceShadow Lass (voice) | Shadow Lass (voice) |
 Jennifer HaleAlura (voice) | Alura (voice) |
 Cynthia HamidiDawnstar (voice) | Dawnstar (voice) |
 Ely HenryBouncing Boy (voice) | Bouncing Boy (voice) |
 Daisy LightfootTriplicate Girl (voice) | Triplicate Girl (voice) |
 Eric LopezCosmic Boy / Chemical King (voice) | Cosmic Boy / Chemical King (voice) |
 Yuri LowenthalMon El (voice) | Mon El (voice) |
 Zeno RobinsonInvisible Kid / Brainiac 3 (voice) | Invisible Kid / Brainiac 3 (voice) |