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 human.

The DoctorDonna was an example of a human with a Time Lord consciousness. She had to be reverted to her human self; her brain could not hold a such a consciousness. The Tenth Doctor had to erase her mind of all knowledge of him. (TV: Journey's End) Despite this, Donna's latent consciousness remained half-Time Lord, 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 Tenth Doctor stated that a human-time lord metacrisis has never happened before because it can't be happened.(TV: Journey's End)

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 occurred. (TV: Journey's End)