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"Maybe cybernetics wasn't such a great idea after all. Look what the demons have done with it. It seems unfair somehow you're not the only guy in Hell with a plasma gun."
― Description in the Doom II manual

The Arachnotron is a spider-like cyborg monster introduced in Doom II. It is similar in appearance to the Spiderdemon, but smaller and with large eyes that change color depending on the monster's current state (moving, hurt, or attacking). It is supported by a metal chassis and a body that consists primarily of a large brain, along with two small arms. Instead of a chaingun, it wields a powerful plasma gun that fires bursts of yellow and green energy.

In Doom II, they make their first appearance in Dead Simple, where the player must fight them when they reinforce the fallen Mancubi.


They are the small offspring of the Spiderdemon that was the final boss in the original Doom. They are nastier offensively, slinging green plasma bolts like pissed off Barons of Hell. But they can't stand the same level of damage as their daddy before going legs up.[1]

Maybe cybernetics wasn't such a great idea after all. Look what the demons have done with it. It seems unfair somehow you're not the only guy in Hell with a plasma gun. [2]

Combat characteristics

An Arachnotron emits a crescendoing mechanical cry (akin to machinery powering up) when spotting a player. Like the Spiderdemon, it has audible footsteps, in their case sounding like buzzing machinery punctuated with occasional electronic crackling. When this monster dies, its head explodes into a morass of gore as its mechanical body collapses while unleashing an electronically-pitched dying tone that resembles failing machinery.

Tactical analysis

Once the Arachnotron engages an enemy it will continue to fire until the enemy is killed or moves out of its field of view, or until the monster itself flinches in pain or is destroyed - similar behavior can be observed with the Spiderdemon, Wolfenstein SS and Heavy Weapon Dude.

Although they may seem slow, Arachnotrons are actually faster than quite a few of the other monsters and can catch up with the player at an alarming rate. They have a medium pain chance, so rapid fire weapons such as the chaingun will work well, although using the chainsaw on them is very risky (unless the chainsaw-wielding player can rapidly reach and attack the monster before it opens fire). Their attacks are easier to avoid than the rapid-fire hitscan attacks of Heavy Weapon Dudes and Spiderdemons, but their plasma bursts are among the fastest projectiles, and their high rate of fire can quickly drain the player's health. Additionally, the plasma bursts can obscure the player's vision upon a successful hit. If a player constantly attacks, moves in broad side-to-side movements, and tries to get out of the Arachnotron's line of fire periodically, then the player will sustain minimal damage.

Because of their sustained, extremely fast rate of fire, they are often more than capable of defeating almost any monster if provoked via monster infighting, especially when multiple Arachnotrons attack; however, stronger enemies such as a Baron of Hell will usually prevail in smaller battles because of their higher health.


ID # 68 (decimal), 44 (hex)
Hit points 500
Speed 12 map units per frame
(140.0 map units per second)
Width 128
Height 64
Reaction time 8
Pain chance 128 (50%)
Pain time 6 tics
Mass 600
Bits 4194310
Bits list

1: Obstacle

2: Shootable

22: Affects Kill %

Sprites & sounds
Sprite name BSPI
Alert sound DSBSPSIT
Chase sound DSBSPWLK
Action sound DSBSPACT
Pain sound DSDMPAIN
Death sound DSBSPDTH
Ranged attack
Type Projectile
Speed 25 map units per tic
(875 map units per second)
Damage 5-40
Shots per minute 263
Width 13
Height 8
Sprite name APLS (in flight)
APBX (impact)
Sound DSPLASMA (firing)
DSFIRXPL (impact)

Damage done by each plasma burst

Shots needed to kill Mean Standard
Min Max
Player (100%
health, no armor)
5.02 1.09 3 8
Player (100%
health, security armor)
7.16 1.23 5 10
Player (200%
health, combat armor)
17.99 1.97 13 22
Barrel 1.44 0.60 1 4
Trooper 1.44 0.60 1 4
Sergeant 1.80 0.75 1 4
Wolfenstein SS 2.75 0.78 2 5
Imp 3.16 0.86 2 6
Chaingunner 3.61 0.91 2 6
Lost Soul 5.02 1.09 3 8
Commander Keen 5.02 1.09 3 8
Demon 7.22 1.29 5 10
Spectre 7.22 1.29 5 10
Boss Brain2 11.68 1.70 8 16
Revenant 13.90 1.83 9 18
Cacodemon 18.27 2.04 13 22
Pain Elemental 18.27 2.04 13 22
Hell Knight 22.80 2.24 17 28
Mancubus 27.28 2.45 21 33
Arch-vile 31.76 2.58 25 37
Baron of Hell 45.16 3.09 36 52
Spider Mastermind 134.41 2.61 128 140
Cyberdemon 179.12 2.55 173 184
  1. This table assumes that all calls to P_Random for damage, pain chance, impact animations, and backfire checks are consecutive. In real play, this is never the case: counterattacks and AI pathfinding must be handled, and of course the map may contain additional moving monsters and other randomized phenomena (such as flickering lights). Any resulting errors are probably toward the single-shot average, as they introduce noise into the correlation between the indices of "consecutive" calls.
  2. Assumes that direct hits are possible, which does not occur in any stock map.
  3. Hardcoded exception to infighting negates damage (excepting indirect damage caused by exploding barrels).


The Arachnotron's sprites have numerous holes in them.

Appearance statistics

In classic Doom, the Arachnotron is first encountered on these maps:

Doom II MAP07: Dead Simple MAP07: Dead Simple MAP07: Dead Simple
TNT: Evilution MAP06: Open Season MAP08: Metal MAP04: Wormhole
Plutonia MAP03: Aztec MAP03: Aztec MAP03: Aztec

The IWADs contain the following numbers of Arachnotrons:

Doom II 15 41 64
TNT: Evilution 29 52 57
Plutonia 68 87 94
  1. Doom II OSG, pg 38
  2. Maybe cybernetics wasn't such a great idea after all. Look what the demons have done with it. It seems unfair somehow you're not the only guy in Hell with a plasma gun.