Previously, Sheard had (briefly) worked with Lucas as the U-boat captain in Indiana Jones and the Raiders of the Lost Ark. In 1978, he had starred in a film version of Les Miserables alongside Kenneth Colley.
He was also known to sci-fi fans for appearing numerous times in the sci-fi series Doctor Who as well as holding the record for actor playing alongside the most Doctors. The stories in which he starred include The Ark (1966), The Mind of Evil (1971), Pyramids of Mars (1975), The Invisible Enemy (1977), Castrovalva (1982), Remembrance of the Daleks (1988) and The Stones of Venice (2001). He also provided the commentary for the Pyramids of Mars DVD.
In what proved to be his final appearance in front of the camera, Michael joined Jeremy Bulloch, David Prowse and Orli Shoshan in the final two parts of UK fan-film trilogy Order of the Sith. Michael read the opening crawl for each film. The films were made in aid of Save the Children—part of a vast range of work Michael did for charity.
He was a heavy regular on the UK science-fiction convention circuit.