Earth-33⅓

Earth-33⅓ was a universe within which the Doctor and various other individuals apparently existed both as real people (COMIC: Doctor Who? 64, The Incredible Doctor Who History Tour (No. 7.), etc.) and as fictional characters in the series Doctor Who. (COMIC: Doctor Who? 87, Ever Wondered What Happened At.. The Auditions For The Seven Doctors?, etc.)

History
To be added

Behind the scenes
"Earth-33⅓" was the main universe shared by the majority of Tim Quinn and Dicky Howett's comic output, both to Doctor Who media, and to other Marvel media. Later Marvel guidebooks often refer to the universe as "Earth-333333333".