Pinky, as well as Brain, is a white mouse who is being kept as part of Acme Labs' experimentation. They have undergone significant genetic alteration; as per the show's title lyrics, "their genes have been spliced" which gives the two mice amplified intelligence over that of a typical mouse.Pinky is the deuteragonist of the series, and the Brain's best friend.
Pinky shares the same cage as The Brain at Acme Labs. Whilst being more open-minded and fun loving, he is notably dimmer than the Brain, and speaks with an exaggerated cockney accent. He has several verbal tics, such as "narf", "zort", "point", and "troz" (the last of which he started saying after noticing it was "zort in the mirror"). He is portrayed as silly, insane, dumb, open-minded, friendly, sensitive, funny, lovable, sweet, loyal and cute.
Despite his cheerful personality, Pinky is very emotional and given to moments of excessive emotional outbursts, usually to the Brain's chagrin.
Pinky has also shown to be very loyal to Brain, seeing as he accompanies Brain almost all the time and going on dangerous or long adventures.
Pinky has a straight tail, blue eyes, and a severe overbite, and is taller than the Brain. He is usually seen with a smile on his face.
Pinky's name was given to him by Brain, thinking that Brain was calling him when in fact Brain was referring to his own pinky digit, when insulting some scientists while talking to himself.
Pinky possesses above-average intelligence for a mouse, and anthropomorphic dexterity, allowing him the use of his front paws as human-like hands.
In one episode, he is shown to have occasional telekinetic powers, which he describes as coming and going when questioned about them by the Brain when the latter sees him levitating a bowl of fruit.