Pinky and the Brain are laboratory mice whose genes have spliced resulting in one being a genius and the other being rather insane (and slow). The Brain, aptly named for his smarts and enormous cranium, constantly schemes to take over the world while Pinky helpless follows the leader despite being mushed, blown up and verbally abused on a regular basis.

This odd couple first appeared as a recurring segment in Steven Spielberg's excellent Animaniacs show and quickly became the most popular characters in that series. Their catchy theme song introduced the two mice and their goal for world domination. A typical exchange between Pinky (who sounded like a British surfer) and the Brain (who sounded like Orson Welles):

Brain: Pinky, are you pondering what I'm pondering?
Pinky: I think so, Brain, but if we hadn't any ears we'd look like weasels.

After being spun off into their own show, Pinky and the Brain were joined by many more characters in their Acme Lab cages. Snowball the hamster used to be Brain's friend; he is super intelligent but slightly more evil than Brain. He harbors the same desire to take over the world. Billie is a girl mouse, object of Brain's affection, nursing a crush for Pinky who remains happily oblivious. Larry, another white mouse, is modeled after Larry Fine from The Three Stooges.

Pinky and the Brain reveled in the same wacky humor showcased in Animaniacs, entertaining to kids and adults simultaneously. Pop culture references flew thick and fast in each episode as did parodies of movies, other cartoon characters, political and historical figures. Brain's erudite manner contrasted with Pinky's  random non-sequiturs  that include involuntary exclamations of "Narf!" and "Zort!" They're nonsense words but do try to include them in your speech as much as possible; your friends will thank you.

In 1998, the show added Elmyra, a Tiny Toons character, whose love for all things furry was swift and merciless. Pinky and the Brain became Pinky, Elmyra & the Brain and the action moved to Elmyra's pink bedroom of horrors where the two mice tried to escape the little girl's clutches. The new format didn't appeal to fans and after cancellation Pinky and the Brain in 1998 moved to cable reruns.