In 1999, Walliams appeared with friend Mark Gatiss in three sketches that parodied Doctor Who: The Web of Caves, The Kidnappers (which also featured Peter Davison) and The Pitch of Fear (in which he played Sydney Newman).
He also played one of his characters from Come Fly With Me, along side Matt Lucas in a 2010 BBC Christmas Ident featuring a Dalek from the new Dalek Paradigm. He also appeared as himself as a Prime Minister in the 2012 BBC Christmas ident titled It's Showtime.
Walliams is better known for his professional partnership with Matt Lucas and for writing and starring in their Little Britain franchise, which was narrated by Tom Baker and also involved Anthony Head and Paul Putner. He has claimed to be a Doctor Who "enthusiast" and got Baker to work on the series because he is such a devotee of the Fourth Doctor.  He has also written many Doctor Who references into Little Britain, such as when he played a character named Matthew Waterhouse.