Донна Ноубл
The Tenth Doctor also consciously aborts a regeneration in "Journey's End" and instead transfers the energy to his previously severed hand (from "The Christmas Invasion"), which had been saved in a container by Captain Jack Harkness; when Donna Noble touches it, it creates an entirely new person - a "meta-crisis" half-human Doctor. The Eleventh Doctor confirms, before himself regenerating during the events of "The Time of the Doctor", that this action used up a full regeneration.