Joe Kapp was played by Simon MacCorkindale, who had previously appeared in "Baby", one of the episodes of Nigel Kneale's "Beasts" series. MacCorkindale was delighted with the part of Joe Kapp, finding it a break from the typecast romantic roles he was used to playing. Following "Quatermass", MacCorkindale appeared in "The Riddle of the Sands" (1979), and subsequently moved to the United States where, after playing a few guest roles on television, he secured a part in "Jaws 3" (1983) and the lead in the short-lived series "Manimal" (1983). He was then a series regular in "Falcon Crest" (1984–86), "Counterstrike" (1990–93) and "" (1999). He then returned to the United Kingdom, where he played the character of Harry Harper in "Casualty" between 2002 and 2008. MacCorkindale died in 2010.