Fugitive Doctor

An incarnation of the Doctor, identified as such by the Judoon and the Thirteenth Doctor's sonic screwdriver, had a history of working for Gallifrey, in a role one did not "apply for", which she sought, though failed, to abandon. At one point, the Doctor hid out on Earth using a Chameleon Arch, taking on a human identity as "Ruth Clayton".

She had her TARDIS buried near the lighthouse where she stored her true identity, and trusted Lee Clayton to protect her, under cover as Ruth's husband. Lee was also tasked with reminding her to "Follow the light and break the glass" when the time was right, as this would lead Ruth to return to the lighthouse, which she was made to recall from childhood, and finally restore her Time Lord memories. (TV: Fugitive of the Judoon)

Working for the Time Lords
to be added

As Ruth Clayton
to be added

Behind the scenes
This incarnation of the Doctor is the first within the DWU to be played by a non-white actor, Jo Martin. Some stories have previously shown the Doctor briefly taking over the bodies of non-white humans, and so getting played by those who were cast for those characters, and others have already indicated that non-white incarnations do in fact exist somewhere along the Doctor's timeline.

Daniel Anthony played the Eleventh Doctor in The Sarah Jane Adventures story Death of the Doctor while he occupied the body of Clyde Langer, and Damian Lynch played the Third Doctor in the audio story Ghost in the Machine while he was using the body of Benjamin Chikoto to communicate.

More concretely, Russell T Davies' Rose novelisation shows that Clive Finch has collected photographs of, among other known incarnations, a tall, black female Doctor who wields a flaming sword.

In 1986, Lenny Henry also portrayed a parodic incarnation of the Doctor in a comedy sketch as part of his BBC series The Lenny Henry Show.