Disembodied brains from an unknown world. They hate conscious thought, which brings them pain. They have dedicated themselves to ridding the universe of intelligent life, one planet at a time using their ability to disrupt the delta wave pattern generated by all animal and robot life, rendering them stupid(er). The only being in the universe immune to this effect is Philip J. Fry, a delivery boy from New New York. It was Fry who prevented the Brain Spawn and their leader, the Big Brain, from destroying Earth, by outwitting him. Upon his defeat, the Big Brain left Earth for no raisin, and the remaining Brain Spawn on Earth were devoured by the Nibblonians.