Tenth Doctor (The Curse of Fatal Death)

A person who logically would have been called the Tenth Doctor was the result of the regeneration of the Ninth Doctor when he fell to Dalek firepower.

Biography
The Tenth Doctor came into being when his previous incarnation regenerated after the Daleks exterminated him on the planet Tersurus. He himself regenerated when trying to fix the Daleks' broken zectronic beam and turned into his next incarnation. (TV: The Curse of Fatal Death)

Psychological profile
Though a short-lived incarnation, the Tenth Doctor showed an overly confident and flirtatious personality, describing himself as "cute, sexy and lick-the-mirror handsome", and openly referring to Emma as "the only companion [he'd] ever had". He also mocked, calling him camp and saying he had "nice tits", which were really Dalek etheric beam locators. (TV: The Curse of Fatal Death)

Behind the scenes

 * In an early draft of the script, written prior to casting, this incarnation was referred to as "The New Doctor", and introduced as follows: "Gone is the suave courtly adventurer, replaced by a handsome, muscular rugby-playing type - the sort of swaggering vulgarian the previous Doctor would have loathed on sight." His final name, used in the behind-the-scenes documentary and in Doctor Who Magazine credits, was "The Quite Handsome Doctor".
 * Richard E Grant voiced an animated version of the Ninth Doctor in the webcast animation Scream of the Shalka.