Morbius

Morbius of House Dvora was a high-ranking Time Lord whose career was the first in millennia to dramatically alter Gallifrey's relationship to the wider universe, briefly moving the world's policy away from observation and manipulation of external affairs and instead towards brutal restructuring of the universe to suit Gallifrey's best interests (DW:The Brain of Morbius, FP:The Book of the War). The Doctor became embroiled in the chaos that resulted (PDA: Warmonger). His career ended in ignominy and destruction, and he escaped a sentence of death only by means of a secret brain transplant, subsequent to which he encountered the fourth incarnation of the Doctor. (DW:The Brain of Morbius).

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

While still based on Gallifrey he formed a personal army composed of both dedicated followers and mercenaries from other species. He promised these followers the secrets of time travel and immortality (DW: The Brain of Morbius) although withheld from them true admission into his House (FP: The Book of the War). During his search for immortality he utilised both the time scoop and the Death Zone drawing seven incarnations of Iris Wildthyme to play the Games of Rassilon in an attempt to gain Rassilon's gift of immortality, though 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), eventually denounced him, he and his followers abandoned Gallifrey and began an assault on the cultures of the external universe (DW: The Brain of Morbius).

As Gallifrey's 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 (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 Lords eventually chose to fight the war by proxy.

The fifth incarnation of 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.

The Alliance eventually defeated Morbius on Karn with the assistance of the Sisterhood and brought to trial, although the verdict had been decided in advance. (PDA: Warmonger) The sentence of death by public and ceremonial disintegration was partly a panicked attempt by the Time Lords to caution the universe at large against opposing them (FP: The Book of the War).

His body was indeed destroyed, with Sisterhood leader Maren among those attending. However, Morbius escaped death when one of his followers, the human surgeon Doctor Mehendri Solon, secretly removed the Gallifreyan criminal's brain before his disintegration.

Taking the brain, 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, which provided a regular supply of corpses from which Solon scavenged body parts for this project (DW: The Brain of Morbius).

Morbius' Brain
Over the years, Solon had 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 Doctor and his companion, Sarah Jane, arrived at his castle, upon the planet Karn.

However, this haphazardly constructed body lacked a head to house the brain of Morbius, and after Morbius's brain was damaged during a fall, Solon was forced to resort to using a plastic brain case. Morbius was unable to speak for some time due to the damage sustained when his brain was dropped. Eventually Solon was able to repair this, but was killed soon afterwards, 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
Zarodnix later became the leader of the Cult of Morbius and bought the planet Karn, forcing the sisterhood off world. There he found a fragment of Morbius' brain and began to look for a Time Lord, so he could extract their DNA to fuse with what was left of Morbius' in order to bring about his resurrection. (BFA: The Vengeance of Morbius)