Max Adrian was cast as inquisitor Ibert (in his second-to-last film performance), while Dudley Sutton, who had become a cult figure for his performance in "The Leather Boys" (1964), agreed to appear in the film as Baron de Laubardemont. Sutton recalled that all of the "respectable actors turned it down. They thought it was blasphemous, which it is not." In the role of Father Mignon, a priest who attempts to usurp Grandier's power, Russell cast Murray Melvin, despite the fact that he was decades younger than the character, who was intended to be in his eighties. Michael Gothard, an English character actor, was cast as self-professed witch hunter Father Barre. Russell cast Christopher Logue, an occasional actor who was mainly known as a poet and literary scholar, as the vengeful Cardinal Richelieu.