In "Dalek" (2005), the Ninth Doctor explains that his people perished along with the Dalek race in the "Last Great Time War", leaving the Doctor the last of his race [REF].
In "Face the Raven" (2015), the immortal Ashildr makes a deal to have the Doctor's TARDIS keys and confession dial taken and to teleport the Twelfth Doctor away in exchange for her trap street's safety [REF].