Eighth Doctor

The TV Movie
The Eighth Doctor's life began when the Seventh Doctor regenerated after being caught in the crossfire of a shootout between rival Chinese-American youth gangs in 1999 San Francisco's Chinatown and dying on the operating table while being attended by Dr. Grace Holloway, who was unaware of, and thus unfamiliar with, the Doctor's alien physiology. Almost immediately, he was caught up in yet another battle with his arch-enemy the Master, whose essence had survived his execution on Skaro and entered the body of a human ambulance driver. Knowing this human body would not last, the Master plotted to use the Eye of Harmony to steal the Doctor's remaining lives. After defeating the Master, the Doctor paid his farewells to Grace and continued on his travels through space and time.

The Expanded Universe
Leaving San Francisco, the Doctor found himself still suffering post-regenerative amnesia. (Indeed, bouts of amnesia would plague the Doctor at many points in this eighth life.) He found himself travelling to different past points in his own timeline, encountering his previous incarnations and one point securing the release of his old teacher Borusa from the Tomb of Rassilon. At the end of this journey, he acquired his newest companion, Sam Jones, a young woman from the same Shoreditch neighborhood where the Doctor stayed in I.M. Foreman's junkyard with his granddaughter Susan ("The Eight Doctors").

This Doctor acquired yet two more companions, Fitz Kriener and Compassion. Together, they would play pivotal roles in the Doctor's battles with Faction Paradox. These battles culminated in the destruction of Gallifrey, and in the Doctor being exiled to Earth for 100 years ("The Ancestor Cell".

Eventually the Doctor would learn that just prior to the destruction of Gallifrey, the sum total of the Matrix was placed within his mind, providing a means to rebuild Gallifrey and restore the Time Lords. The Doctor set out to do just this with the assistance of the Time Lord Marnal ("The Gallifrey Chronicles"). Presumably it was this new Gallifrey that was destroyed in the last Time War, and it was during this battle between the Daleks and the Time Lords that the Eighth Doctor lost his life, regenerating into the Ninth Doctor.

Characteristics
The Eighth Doctor was more romantic than his predecessors, and much more open in his admiration for humans. While earlier Doctors, especially the First and Seventh, would be visably exasperated by human failings and quirks, this Doctor was more likely to be quitely amused. This may be due to his being half-human on his mother's side, a secret the previous Doctors never revealed.

Habits and Quirks
The Eighth Doctor had a penchant for late 19th Century style clothing, beginning with a Wild West costume he stole from a hospital worker's locker shortly after his regeneration.

Mysteries and Discrepancies
The Eighth Doctor claims to be "half human, on my mother's side," and this is confirmed by the Master. This may explain why the Doctor never seemed to "fit in" with his fellow Time Lords.

Quotes
"I'm half human, on my mother's side."