Popeye

Popeye was a comic strip featuring a character of the same name. Malcolm enjoyed reading it when he was six years old in 1963. It had a character named Wimpy, who lent his name to London's Wimpy Bar. (PROSE: Time and Relative)

The Fourth Doctor whistled the theme to Popeye while visiting a Shanghai dock in 1937. (PROSE: The Shadow of Weng-Chiang)

While stuck in Sol Transit System, the Seventh Doctor tries to keep himself from disassociating by flying apart down all the logical pathways of probability by telling himself "I am what I am what I am." This results in part of himself detaching and spinning down an alternative pathway where he becomes Popeye the Sailor Man. (PROSE: Transit)

Other than Popeye, characters includeed Olive Oyl and her brother Castor. The Tenth Doctor joked that the spaceship Castor may have been named after him. (PROSE: Wooden Heart)

Behind the scenes
The Popeye comic strips were published alongside those of Doctor Who in TV Comic. Its characters appeared on the covers of the TV Comic Annuals, occasionally depicted alongside the Doctor or some other elements from their universe.