Elvis Presley. The King. And the origin of approximately three sevenths of all Mark's stories on Wittertainment.
The story of Elvis "turning up to the White House loaded" and asking to meet Richard Nixon has in fact become a film, called, er, Elvis And Nixon.
In his younger days at Radio 1, Mark once stormed out of a discussion with Mark Radcliffe when Radcliffe insisted that Elvis was, in fact, dead. The Good Doctor had a different view, and believed that the lack of answers to a number of interesting questions ("why was the corpse sweating?") suggested that the King still lived.
Indeed, the theory is that Elvis faked his death and came back as an Elvis impersonator called Orion, who was then somehow linked to Orion Pictures, which made The Silence Of The Lambs. Earlier in his career, Elvis had been offered the Kris Kristofferson role in A Star Is Born, but had been forced to turn it down by Colonel Tom Parker ("he wasn't a colonel and Tom Parker wasn't his name. Other than that, he was completely honest") who would not let him take second billing to Barbara Streisand. But by virtue of its success at the 1992 Oscars, Silence finally allowed Elvis / Orion to claim the Oscar he had always been denied.
Newsreader Justine Green was another BBC employee who infuriated Mark, by mentioning the story of Jay-Z having more UK Number One albums than Elvis in every bulletin that afternoon.