|First appearance||"The Day the Earth Stood Stupid" (3ACV07)|
The Brain Spawn are a race of big, flying brains who travel from planet to planet and destroy all sentient thought, which they hate, eventually eliminating the planet in question. They came into being milliseconds after the Big Bang. They have been at war with the Nibblonians ever since. The ultimate goal of the Brain Spawn is to gather all the knowledge in the universe. This ultimately leads to the construction of the Infosphere. Once all information in the known universe is collected, the Brain Spawn intended to destroy the universe, to ensure that no new information would be created. The Brain Spawn cannot see; they only can detect the Delta Brain Waves of a sentient being. Their chief combat ability is to send out a stupefication field that eradicates all intelligence within the blast radius--presumably the field attacks the Delta Brain Wave itself. This makes Philip J. Fry the ultimate champion against the Brain Spawn, as he lacks the Delta Brain Wave and therefore can neither be seen nor fought by them. The Brain Spawn hate conscious thought for several reasons, among which is the fact that thought by others than themselves hurts them. This is one of their few weaknesses.
The Brain Spawn have three apparent classes:
- Small Brains: Foot soldiers of a sort, but have huge numbers. Capable of stupefying an entire planet in a matter of hours.
- Big Brains: A sort of "General", more intelligent, capable of speech, and can trap beings in fictional worlds created from books.
- Huge Brain: Only one ever seen, capable of firing a beam that can instantly kill large dinosaurs.
 Racial Abilities
- Flying ability
- Stupefaction Field
- Interstellar travel
- Survival in most enviroments, including the vacuum of space
 Additional Info
- Fry appears to be referring to the Brain Spawn when talking to Michelle in "The Cryonic Woman"; as he had not actually met them yet, this was probably in reference to something else, such as the Spheroids.
- Some planets destroyed by the Brain Spawn are Space Rome, Don Martin 3, and Tweenis 12.
- The Brain Spawn are responsible for the destruction of the dinosaurs.
- Dwight Conrad, Chinese Boy and Indian Boy dress as Brain Spawns during the costume contest at Comic-Con Intergalactic in 3010.(6ACV11)
- It is unknown why the Brain Spawn are in the form of human brains, having come into being billions of years before the humans.
- As of yet, the Brain Spawn are currently the first known alien race to make contact with Earth (but not with humans).
The Big Brain: I'm a gigantic brain!
The Big Brain: The big brain am winning again! I am the greetest! Now I am leaving Earth for no raeson?!
Fry: What really killed the dinosaurs?
Huge Brain: ME!!!!
Brain: Our calculations are always correct, for we are gigantic brains.
Brain: A Quantum Interphase Bomb? Are you insane in the membrane?