Sources report that Bela Lugosi and Claude Rains were considered, with varying degrees of seriousness, for the role of Frankenstein's mentor, Pretorius; others report that the role was created specifically for Ernest Thesiger. Because of Mae Clarke's ill health, Valerie Hobson replaced her as Henry Frankenstein's love interest, Elizabeth. Early in production, Whale decided that the same actress cast to play the Bride should also play Mary Shelley in the film's prologue, to represent how the story — and horror in general — springs from the dark side of the imagination. He considered Brigitte Helm and Phyllis Brooks before deciding on Elsa Lanchester. Lanchester, who had accompanied husband Charles Laughton to Hollywood, had met with only moderate success while Laughton had made a strong impact with several films including "The Private Life of Henry VIII" (for which he had won an Oscar) and Whale's own "The Old Dark House". Lanchester had returned alone to London when Whale contacted her to offer her the dual role. Lanchester modeled the Bride's hissing on the hissing of swans. She gave herself a sore throat while filming the hissing sequence, which Whale shot from multiple angles.