Octabrain may refer to:
- Octabrain (DN3D), an enemy in Duke Nukem 3D
- Octabrain (DNF), an enemy in Duke Nukem Forever
Other uses:
- Jellyfish, an early version of the Octabrain seen in LameDuke
- Necro, an enemy that is easily mistaken for an Octabrain in Duke Nukem: Time to Kill
- Necrobrain, a cybernetically enhanced Octabrain in Duke Nukem: Land of the Babes