Original Appearances: Inspector Gadget, 1983-1986
Other Appearances: Inspector Gadget live-action movie, 1999, cameo in an episode of Robot Chicken, and Inspector Gadget comic book starting in 2011. There was probably Gadget merchandise featuring Brain.
Biography: Brain is the faithful dog of Inspector Gadget and his niece, Penny. Brain is bipedal, and assists Penny in keeping Gadget out of trouble and solving the crime. He's a master of disguise (Gadget never sees through them, anyway, often mistaking him for a M.A.D. Agent). He's able to communicate with humans just fine, and wears a collar that includes a retractable video communications system linked to Penny's watch. Doctor Claw is apparently entirely unaware of the role Brain and Penny play in helping Gadget succeed – then again, neither does Chief Quimby, apparently!
Powers: Walking bipedal and having human intelligence.
Group Affiliation: Gadget family.
Miscellaneous: It was surprising to me to find that there were only two seasons made, given the show continued to be in syndication for so long! Then again, there were 86 episodes in those two years. Inspector Gadget, of course, was voiced by Don Adams... and the Brain was voiced by Frank Welker, because, hey, who else do you hire to do a dog's voice?