Clarence

Biography
Clarence was originally named Gabriel by God except Bernice Summerfield (upon meeting him) decided that 'Clarence' suited him better. (BNA: Ghost Devices)

Clarence was a sentient ship known as !C-Mel, but due to an 'accident' which for much of his life he couldn't remember the specifics of, but which involved the Doctor. (NA: The Also People)

Clarence was God's representative in the Milky Way as he didn't register as a member of The People, and therefore his presence (as a monitor/spy) did not break the Time Lord-People treaty. (BNA: Ghost Devices)

Clarence resembles Keanu Reeves, only with wings and generally he's naked. (BNA: Ghost Devices)