King Nocturne
From Tardis Wiki, the free Doctor Who reference
This topic might have a better name.
OncomingStorm12th proposes a new name "Nocturne (The Singer Not the Song)"; Amorkuz proposes a new name "King Nocturne"
Talk about it here.
The Nocturne was a conceptual being imprisonned inside another universe along with Sutehk and a number of other godlike beings who were a threat to the Doctor's universe. (COMIC: The jazz monster)