Human-Time Lord Meta-Crisis

Human-Time Lord Meta-Crisis was the term applied to a hybridised organism that combined the traits of a Time Lord and a human.

The DoctorDonna was an example of a human with a Time Lord consciousness. The Tenth Doctor stated that a Human-Time Lord Meta-Crisis had never happened before because it was unsustainable. Donna had to be reverted to her human self; her brain could not hold a such a consciousness. The Doctor erased her mind of all knowledge of him. (TV: Journey's End) Despite this, Donna's latent consciousness retained at least some non-human aspects, protecting her when turned the world into copies of himself. Apparently, it also subconsciously guided her to buy a book for her grandfather, which led the Doctor and him to Joshua Naismith. (TV: The End of Time)

The Meta-Crisis Doctor seemed to be a mixture of the two races. He did not burn up, presumably having a Time Lord brain, but only had one heart and could not regenerate. He also showed quirks of Donna Noble, the human with whom the Meta-Crisis had occurred, specifically her urge to argue and say "Oi!". (TV: Journey's End)