The Eighth Doctor (Paul McGann)
The Eighth Doctor, played by Paul McGann, led a life of unusual temporal complexity. It so frequently involved time paradoxes and parallel universes that it was impossible to know with certainty how the major epochs of his existence fitted together. Complicating the matter even further were his frequent bouts of amnesia, as well as several phases of his life where he lived in one place for more than a hundred years, such as Earth and Orbis .
He was unique amongst incarnations of the Doctor in that he was technically dead both when he regenerated from the Seventh Doctor and when he regenerated into the War Doctor. Additional factors that made him unique included him being the only Doctor to travel with an Ice Warrior, the first to have significant interaction with his granddaughter after his first incarnation left her behind on Earth and one of the few to have had sexual relations with at least one of his companions.
The Eighth Doctor was inherently a happy adventurer, falling in love with companions Grace Holloway and Charlotte Pollard, and was not averse to experiencing and appreciating very human emotions, from kissing Grace to providing psychological support for Izzy Sinclair. So strong was his affection for humans, that he even claimed to be half-human — though this was later revealed to be a clever ploy against the Master.
At his core an optimist and a romantic, the Doctor tried to remain a cheerful and pacifistic adventurer in spite of a universe that grew ever increasingly hostile around him, eventually culminating in the eruption of the Last Great Time War between the Time Lords and the Dalek Empire. Despite his efforts to stay out of the war, the Doctor eventually succumbed to despair as the war started to threaten all of existence, and when presented with an option to choose the traits of his next incarnation, he chose to become a warrior in the hopes of ending the war once and for all.