The Brain is the intelligent megalomaniac mouse that harbors a long-lasting desire to take over the world. He is often annoyed by Pinky's silliness and often thought of complicated plans to take over the world. However, he notes that since he was really smart, that he could make the world a better place.
In “You'll Never Eat Food Pellets In This Town Again”, Brain has a wife named Sheila who apparently plays Billie. However, this episode was non-canonical and was meant to joke on the WB's petty executives. Brain is heavily based on Orson Welles, in both how he speaks and how he looks. At one point he even tried to copy Orson's infamous radio telling of War of the Worlds.
The Brain: "The same thing we do every night, Pinky—try to take over the world!"
- Black rhino ranger used a Koala model to create The Brain.