Fourteenth Doctor

The Fourteenth Doctor was the result of his predecessor's solitary regeneration after saving the Earth, and was mystified by his own resemblance to the Tenth Doctor.

A day to come
When encountering the "Vortex Butterfly", the Tenth Doctor was cryptically told that he would not be "limited" to "thirteen lives". (COMIC: Vortex Butterflies)

The Curator had told the Eleventh Doctor that he might find himself revisiting old faces. (TV: The Day of the Doctor)

A new body
After spitefully used his Tissue Compression Eliminator to direct the Qurunx's destructive blast at the Thirteenth Doctor — as he believed that if he couldn't be the Doctor, then neither could she — it fatally wounded her. Fighting off the regeneration long enough to have one last conversation with Yasmin Khan, she went to a cliff, by herself, to regenerate. Unusually, after saying her farewells to herself and regenerating into her new incarnation, the Doctor found himself taken aback by the fact that he was in a body all-too-familiar, complete with a different set of clothing, noting his teeth and repeatedly exclaiming "what". (TV: The Power of the Doctor)

Psychological profile
to be added

Appearance
The Fourteenth Doctor, upon regeneration, wore a costume distinct from his predecessor's ensemble. His attire included a white button-up shirt, with a paisley tie, loose fitting tartan waistcoat and trousers. He also wore a navy blue trenchcoat and Converse shoes. He greatly resembled (TV: The Power of the Doctor) his tenth incarnation. (TV: The Parting of the Ways, The Christmas Invasion, et al.)

Behind the scenes

 * This Doctor's numbered designation was officially confirmed by Russell T Davies in a news article posted to the official Doctor Who website following the episode's broadcast.