The film starred Leonard Whiting as Victor Frankenstein, Jane Seymour as Prima, David McCallum as Henry Clerval, James Mason as Dr Polidori and Michael Sarrazin as the Creature. James Mason's wife, Clarissa Kaye-Mason also appeared in the film. The character of Dr Polidori, who did not appear in the original novel, was based on the real-life John Polidori, an acquaintance of author Mary Shelley who was part of the competition that produced her novel. Polidori's own contribution was the first modern vampire story The Vampyre (1819).