Human-Time Lord Meta-Crisis

A Human-Time Lord Meta-Crisis was the term applied to a hybridized organism that combined the traits of a Time Lord and Human. Only two have been known to exist - the "DoctorDonna" and the Meta-Crisis Tenth Doctor. The DoctorDonna had to be reverted to her Human self, as Human brain could not hold a Time Lord consciousness forcing the Doctor to erase Donna Noble's mind of all knowledge pertaining to him. (DW: Journey's End)