The Spidermind (also known as the Spider Mastermind or Spiderdemon) is the leader of the forces of Hell in DOOM. The Spider Mastermind appears as a creature with an immense exposed brain, two useless arms and relatively humanoid facial features. Incapable of movement on its own, it is grafted to a four-legged chassis that provides movement and possibly life support. The Spidermind is armed with a "Super Chaingun" that launches explosive rounds. The Spidermind, alongside the Cyberdemon, leads an invasion of Hell's forces to dominate the UAC facilities on the twin moons of Mars; Phobos and Deimos.
The Spidermind resides in the city of Dis and was killed by a lone UAC Marine. It is possible that, after this event, the Icon of Sin decided to demote the Spidermind to a similar level of a Cyberdemon.