Sheard had a lengthy affiliation with science fiction, and appeared in six televised stories of the BBC science fiction television series "Doctor Who", appearing with the First Doctor in "The Ark" (1966), the Third Doctor in "The Mind of Evil" (1971), the Fourth Doctor in both "Pyramids of Mars" (1975) (for which he later recorded a DVD commentary) and "The Invisible Enemy" (1977), the Fifth Doctor in "Castrovalva" (1982) and the Seventh Doctor in "Remembrance of the Daleks" (1988). He also worked with the Eighth Doctor in "The Stones of Venice", a "Doctor Who" audio drama produced by Big Finish Productions. He was a regular guest at both "Doctor Who" and "Star Wars" conventions over the years in the U.S. and the UK.