Dark Bunny

In the rain-drenched streets of Dark City where the sun never rises, only one person stands between crime and humanity...The Dark Bunny is a superhero.

Although first said to be cousins, it is later revealed that he and Bionic Bunny are twin brothers. When Bionic Bunny and Dark Bunny were born, the two were separated at birth. Dark Bunny was taken by an evil witch and Bionic Bunny was taken by a robot. Being raised by a witch made him not only dark, but actually evil; until Mary Moo Cow taught him to be good. His debt to Mary partially explains why his show was one day cancelled to make room for Mary Moo Cow to air reruns.

Although the Dark Bunny show did not start until "That's a Baby Show!," the episode "Double Dare" reveals that the superhero poster in the Tree House (which has been there since Season 1) is of Dark Bunny.

Trivia

 * He is a parody of Batman.