Tenth Doctor

Benefiting from the healing undergone by his predecessor, the Tenth Doctor possessed an outgoing, lively and genial demeanour that hid his underlying guilt, but it was still present and would appear if the Doctor was overwhelmed.

For most of his life, the Doctor was able to successfully project a convivial and even frivolous front. However, when he had to engage in conflict, the Doctor's energies would shift to reveal a fiercely protective man who resolutely guarded what he held dear, and who could be viciously unforgiving to the forces that dared menace them.

He was unique in that he was the only incarnation of the Doctor who chose to abort one of his regenerations after being hit by a Dalek ray, channelling the energy into his spare hand without changing his appearance, something his successor would attribute to suffering "vanity issues at the time".

Many of his relationships with companions were shaped, to one degree or another, by romance; he seemed to genuinely love his first companion, Rose Tyler, as the person who helped heal some of the scars of the Time War, was completely oblivious to Martha Jones' obvious affections toward him, and insisted upon a platonic relationship with Donna Noble. The departure of each of these companions marked periods in his life where he would abstain from having companions at all, and on one occasion he even stopped having adventures or leaving the TARDIS, with little more than a cat for company.

When travelling without companions, the weight of being the last Time Lord became much more pronounced. If prodded too much, he would erupt in an often righteous sense of fury. Indeed, the Tenth Doctor was described by the Moment as "the man who regrets". The fact that he was instantly able to recall the number of Gallifreyan children that he believed had been killed during the war indicated just how keenly he continually felt those horrendous memories.

He met his eventual end after he absorbed a huge quantity of nuclear radiation whilst saving the life of Donna Noble's grandfather, Wilfred Mott. Delaying the process to visit all of his companions, the Doctor finally regenerated in the TARDIS, causing a huge amount of damage due to delaying the regeneration for as long as he did, and leaving his successor crashing straight for Earth.