Morbius

Morbius, a dictatorial figure on the High Council of the Time Lords, was rejected when he attempted to encourage his people into global domination. The Time Lord raised a vat army which wreaked havoc throughout the universe, until they were defeated by the Time Lords on Karn. Despite his public execution, the brain of Morbius survived, preserved in the nutrients by Solon who, trying to escape notice, constructed a body and a braincase in which to house it. Morbius' weakened brain was destroyed in a mindbending contest with the Doctor who collapsed and almost died from the strain.

The Morbius monster was a hybrid constructed by Solon (Doctor Mehendri Solon, a surgeon who became a follower of the cult of Morbius) as a body for Morbius, and it comprised of various parts of unfortunate aliens, including a huge claw, a plastic braincase and the arm of Condo, Solon's servant. Solon reconnected the brain but, despite his modifications, the creature was again driven mad and eventually forced over a cliff by the Sisterhood of Karn.