Physical description: Moderately tall and lean, with close-cropped brown hair, grey eyes and to him, an annoyingly large nose and prominent ears. Usually seen wearing a scuffed and worn, just above thigh-length black leather jacket over a red or green or dark blue V-neck sweater (or 'jumper' in Brit-speak) and black trousers over black leather oxfords.
Also has a Northern English accent, or what sounds like one. Lots of planets have a north.
Personality: He's generally darkly cheerful and charming in a somewhat manic way (relative to some of his regenerations, he seems to have a somewhat darker, grumpier personality, albeit in a snarky-cool uncle sort of way). Has a sharp, somewhat snarky sense of humor; can be a bit gruff and grumpy, even snappish when someone deserves a good tongue-lashing, and at times rather aggressive and even violent (particularly if a Dalek is in front of him), compared to previous versions of himself. Can come off a bit condescending toward human goofiness or stupidity, but it's hard not to be that way, when your race is(/was) a lot more intelligent and technologically advanced relative to humans. Even still, he's a compassionate individual, though he's thankfully not a bleeding-heart sort. Likely, this stems from bearing the weight of the destruction of the Daleks and the loss of his own race, during the last Time War. Even still, for all this darkness, he embraces life and its moments of happiness with zest and joy: any chance for delight and joy are welcomed with a gleeful, ear to ear grin (his famous "Ev'rybody lives!" at the end of "The Doctor Dances" had this typist cheering with him)!
Short biography: Short biography... of 900 years of time traveling... Before the typist's brain asplodes, perhaps a link or two will do??
He is, as he'll someday call himself whilst wearing another face, a madman in a blue box. He's the last of the Time Lords, born on the planet Gallifrey nine-hundred years ago, and the sole survivor of the Last Time War, which destroyed both the Time Lords and the Daleks whom they fought. Since then, he's been traveling the expanse of space and time in a "borrowed" Type 40 TARDIS (Time and Relative Dimension In Space, basically a time machine), now disguised as a 1950s British police box, due to a jammed chameleon circuit, and with a variety of companions at his side. Along the way, to paraphrase another writer who has played in his universe (officially), he finds himself in some troublesome situation in time and space, and always does his best, even when he doesn't quite succeed, to make that situation better or at least less troublesome than when it found him.
More recently, after an Eighth regeneration of which nothing official has said (off the record, in a comic book-style story that has not yet made it to print due to executive concerns, it would have involved exposure to the Time Vortex during a confrontation with the Cybermen), he's been traveling in the company of Rose Tyler, whom he first encountered during a muddle in London involving animated dress shop dummies and predatory wheelie bins, and which lead to traveling to see the end of the earth, encounters with interplanetary gangsters trying to sell off the earth to the highest bidder, and meeting Charles Dickens at Christmas, with ghosts (that turned out to be more than ghosts). More recently, after a detour through London at the time of the Blitz, he's been traveling with her and one Captain Jack Harkness (prior to the latter's becoming a fixed point in time).
Physical Abilities: Running, often after things, or away from things when the need arises. Also is fairly proficient with firearms (often fairly big-ass ones, in canon), which is an interesting departure from his predecessors.
Superhuman Abilities: He's a lot more resilient to physical damage than human beings (also has two hearts) and in extreme situations, is able to regenerate into a completely new form (though that's not likely to happen at the Mansion). His intelligence is way beyond genius level as we know it: he's an excellent problem solver and good at detecting or figuring out weaknesses, also plotting strategies.
Unusual or Magical Possessions: Will be arriving with his sonic screwdriver, yet sans TARDIS (to his annoyance)