Morbius

Morbius of House Dvora was a notorious and evil Time Lord. His career was the first in millennia to dramatically alter Gallifrey's relations with the wider universe. He briefly broke Gallifrey's Non-interference policy in favour of a brutal restructuring of the universe to suit Gallifrey's interests. (DW:The Brain of Morbius, FP: The Book of the War)

The Imperator Crisis
Morbius's ambition led him to become the head of the High Council. His warlike nature led him to urge the Time Lords toward a policy of conquest (DW: The Brain of Morbius). He demanded the Laws of Time and the Spiral Politic to be redrawn to better suit Gallifrey's needs. (FP: The Book of the War)

While based on Gallifrey, he formed a personal army of dedicated followers and mercenaries, the Cult of Morbius, made up of representatives of other species. He promised his followers the secrets of time travel and immortality, (DW: The Brain of Morbius) but withheld from them admission into his House. (FP: The Book of the War)

In his search for immortality he used the time scoop and the Death Zone. He drew seven incarnations of Iris Wildthyme to play the Games of Rassilon in an effort to gain Rassilon's gift of immortality. This attempt was ultimately thwarted. (EDA: The Scarlet Empress)

When the Time Lords, spurred by the Order of the Weal, (FP: The Book of the War) finally denounced him, he and his followers abandoned Gallifrey and attacked the cultures of the outside universe. (DW: The Brain of Morbius) Gallifreyan society struggled to understand these inconceivable events. The long-term cultural changes brought about would include the increased influence of the Celestial Intervention Agency and the founding of House Paradox, later known as Faction Paradox. (FP: The Book of the War)

War with The Alliance
Unsure how to respond to the physical campaign of conquest Morbius was waging against the universe, (FP: The Book of the War) the Time Lord High Council eventually chose to fight the war by proxy.

The Doctor, who had travelled into Gallifrey's past, was appointed 'Supreme Coordinator of the Alliance Battle Fleet' and directed an unlikely army of humans, Draconians, Cybermen, Ogrons, Ice Warriors and Sontarans against Morbius. Planets involved in the conflict included Fangoria, Romark, Darkeen, Martak and Freedonia which provided troops for Morbius, and Sylvana, Zandir, Tanith and Electra which fell to him. (PDA: Warmonger)

The Alliance at long last defeated Morbius on the planet Karn with the help of the Sisterhood, (PDA: Warmonger) who had originally come from Gallifrey themselves (NA: Cat's Cradle: Time's Crucible). They brought him to trial, although the verdict had been decided in advance. (PDA: Warmonger) The sentence of death by public and ceremonial disintegration was in part a panicked attempt by the Time Lords to caution the universe at large against opposing them. (FP: The Book of the War)

Morbius's body was destroyed, with Sisterhood leader Maren among those attending. However, Morbius escaped death when one of his followers, the human surgeon Mehendri Solon, secretly removed the Gallifreyan renegade's brain before his disintegration. Solon went into hiding on Karn, where he began planning to build a new body for Morbius. The Sisterhood's means of defending the Elixir of Life was to cause nearby spacecraft to crash. This provided a regular supply of corpses from which Solon scavenged body parts for his project. (DW: The Brain of Morbius)

This accepted account of Morbius's downfall could be inferred to be part of the Great Houses' propaganda series known as The Houseworld Chronicles. (FP: Newtons Sleep)

Morbius' Brain
Over the years, Solon acquired a great many body parts, which he used to create Morbius's new body. These included lungs from a Birastrop, a left hand from Solon's unknowing assistant Condo, and a giant lobster-like right hand. This plan to create a new body for Morbius was nearing completion, when the the Fourth Doctor and his companion Sarah Jane, arrived at his castle upon the planet Karn.

The haphazardly-assembled body lacked a head to hold the brain of Morbius. After Morbius's brain was damaged during a fall, Solon was forced to use a plastic brain case. Morbius was unable to speak for some time due to the damage sustained. Eventually Solon was able to repair this, but was killed soon afterward when the Doctor poisoned him with cyanide gas. Morbius then staged a mind-bending contest against the Doctor. After the duel, Morbius was in a dazed, animalistic state. He did not speak again, only groaning in agony. Upon leaving Solon's castle, he was chased by the Sisterhood of Karn, surrounded and forced over a cliff, apparently falling to his death. (DW: The Brain of Morbius)

Vengeance
Cristophe Zarodnix later became the leader of the Cult of Morbius and bought the planet Karn, forcing the Sisterhood off-world. On Karn, he found a fragment of Morbius' brain and began to look for a Time Lord, so he could extract DNA to fuse with what was left of Morbius, in order to effect his resurrection. (BFA: The Vengeance of Morbius)

Behind the scenes
Morbius was named after a character from the 1956 film Forbidden Planet.