This page refers to the Duke Nukem 3D enemy. For other uses, see here.

The Octabrain is an enemy in Duke Nukem 3D. It is first encountered in the second level of L.A. Meltdown, Red Light District.

Description Edit

The Octabrain is a large beige floating brain with tentacles, mean eyes and big teeth. It can expertly use incredible psychic powers, both as a means of movement and as a weapon. It also seems to be the most intelligent enemy in the game, a theory heavily inspired by the size of its brain.

It seems to follow its own agenda, rather than that of the invading aliens. While the other aliens are attacking places and using excessive force to invade Earth, the Octabrain lurks in the shadows. It can often be found guarding nests of Protozoid Slimer Eggs (with babes trapped in slime/vines sometimes nearby), an observation that has grown into the theory that the Octabrain and the Protozoid Slimer are related. It is at home both underwater and on land, and is the most notable underwater-based enemy.

Appearance Edit

The Octabrain is a floating three-eyed beige octopus-like creature. Its body seems to be shaped like a human brain, hence this creature's name. It has two ridges of white spikes running along the top of its body from front to back, a large mouth with lots of teeth, and two white spiked mandibles on each side of its mouth. Its beige body has some brown stripes on it. It has a number of short fleshy tentacles, which dangle uselessly below it. It has three large red eyes, with the third eye being above and between the other two.

Combat analysis Edit

Weapon effectivenesses
Mighty Foot
18 kicks
30 shots
2 shots
Chaingun Cannon
20 shots
1 rocket
2 pipebombs
1 blast
Microwave Expander
13 shots
1 rocket
Laser Tripbomb
2 mines
7-9 shots
  • Note: The values given for the Shotgun and the explosive weapons are minimum values only.

The Octabrain is a fearsome opponent. As well as being able to levitate and fly anywhere, it is perfectly comfortable underwater, and is therefore the primary underwater enemy.

It attacks in two ways. The first way is to approach its foe and bite at it with its large and vicious mouth. Its second and more common method of attack is to charge up and fire at the foe a projectile orb of purple/red psychokinetic energy, which can cause a significant amount of damage. This attack is dubbed a Mental Blast, for a number of reasons (although it may be called several other things too). Firstly, the Octabrain's appearance of a giant floating brain suggests that it can use significant psychic powers (least of all to use them to levitate). Secondly, when charging the attack, its brain and eyes glow red. Thirdly, there is no indication whatsoever that it is an attack from a mechanical object (i.e. a weapon), so psychic powers are the second explanation.

The Octabrain needs to charge up its Mental Blast attack, a process which takes a second. During that moment, it will flinch if shot, which delays (not cancels) the Blast from being fired. This is a useful thing to remember. Also, the Mental Blast can be dodged, as it travels relatively slowly (about the same speed as a rocket).

The Octabrain will often travel in groups, making it an even more deadly opponent. It is also often found lurking around a number of Protozoid Slimer Eggs, which will then hatch to release yet more enemies to worry about. The Octabrain tends to lurk underwater, in alien/mutated areas and in various other dark and dank areas.

An Octabrain is fairly sturdy, and can take a significant amount of damage, so much that it needs 1 rocket from the RPG to kill it. However, it can be killed by any weapon, even if it may require a sizable amount of ammo in order to do so.

Therefore it's arguably the best choice to use the Shrinker to shrink the Octabrain and then stomp it with the Mighty Foot.

Data Edit

Hit points175
32 (Shrunk)
Pain chance25% (64/256)
Scale40 x 40
Sprites & sounds
Actor tile number1820/OCTABRAIN
Alert soundoctarg.voc
Action soundoctarm.voc
Pain soundoctapn.voc
Death soundoctady.voc
Mental Blast Attack
Actor tile number1360/COOLEXPLOSION1
Bite Attack
TypeHealth access
Rate0.8 hits/second


The Octabrain appears in LameDuke as the “Jellyfish”, but is vastly different from its final incarnation in looks and behavior. The LameDuke version is much darker and has a pink brain. Its only attack is to swipe at the player with its front tentacles for no damage.

Concept art for this version of the Octabrain is included with the XBLA version and GoG re-release of Duke Nukem 3D. It shows that the LameDuke Jellyfish was supposed to be able to hide under debris and take control of human remains in order to fire their gun. Obviously, none of these concepts appear in the LameDuke version of the Octabrain.





  • A common bug can cause a shrunken enemy to behave like a normal (unshrunken) enemy. Because of the shrunken enemy's small size, therefore, it is difficult to kill.
    • The bug is caused when the enemy flinches after being shot in its shrunken state.
  • When Duke kills a babe trapped in a cocoon, an Octabrain will often spawn nearby.
  • What appears to be an early version of the Octabrain appears in LameDuke. It has a smaller brain, longer tentacles and colored differently, giving it a mechanical appearance.
  • Some believe that the Protozoid Slimer is the infant form of the Octabrain.
    • This theory is supported by Octabrains and Protozoid eggs often appearing together in Duke 3D.
  • Despite having 175 health, it is very vulnerable to the Devastator, and requires only one rocket to kill it. This is unusual, as the Enforcer and Pig Cop each require four rockets to kill them, even though they both have just 100 health (but they are wearing armor, while Octabrain is completely unprotected).

Octabrains in other gamesEdit

Duke Nukem 3D
Episodes L.A. Meltdown | Lunar Apocalypse | Shrapnel City
Plutonium PAK: The Birth
Anniversary Edition: Alien World Order
Items Access Card | Holoduke | Jetpack | Night Vision Goggles | Portable Medkit
Protective Boots | Scuba Gear | Steroids
Health: Small Medkit | Large Medkit | Atomic Health | Armor
Scrapped: Space Suit | Shield
Weapons Mighty Foot | Pistol | Shotgun | Chaingun Cannon | RPG | Pipe Bomb | Shrinker
Expander | Devastator | Laser Tripbomb | Freezethrower | Incinerator
Scrapped: Flamethrower | Laser Chainsaw | Sonic Resonator | Tazer | Plasma Cannon
Enemies Common enemies: Assault Captain | Assault Commander | Enforcer | Assault Trooper | Battlelord Sentry | Octabrain | Pig Cop | Protozoid Slimer | Recon Patrol Vehicle | Sentry Drone | Shark | Turret
Plutonium PAK: Pig Cop Tank | Protector Drone
Anniversary Edition: Firefly Trooper | Cycloid Sentry | Overlord Sentry
Bosses: Battlelord | Overlord | Cycloid Emperor
Plutonium PAK: Alien Queen
Anniversary Edition: Cycloid Incinerator
Scrapped: Alien Queen Sentry | Bat | Captain | Drone | Drone 2 | Femanoid | Mandroid
Organic Turret | Scorpion Tank | Snake Head | Trooper | Turret
Expansion packs
and add-ons
Duke Assault | Duke Nukem 3D Level Design Handbook (CD levels) | Duke Caribbean: Life's A Beach | Duke: Nuclear Winter | Duke It Out In D.C.
Duke Xtreme | Duke!ZONE | Duke!ZONE 150 | Duke!ZONE II | Plutonium PAK | Duke Nukem's Penthouse Paradise | Unofficial expansion packs
Fan community User maps | Mods & Total Conversions | Speedruns
Source ports | High Resolution Pack
Other Difficulty | Hazards | Multiplayer | Cheat codes | Easter eggs
Quotes | Music | Duke Nukem
Build engine | Game bugs | Unused data | LameDuke
Episodes Mrr Caliber | Mission Cockroach | Suck Hole | Hard Landing
Items Holoduke | Jetpack | Oxygen Tank | Shield | Steroids
Health: Soda Can | Six-pack
Weapons Tazer | Pistol | Plasma Cannon | Pipe Bomb | RPG | Sonic Resonator
Enemies Bat | Captain | Drone | Drone 2 | Femanoid | Mandroid
Jellyfish | Protozoid Slimer | Shark | Trooper | Turret
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