I like films in which the rapist is not a man, or even human. Like Evil Dead, where a girl is raped by a tree. Another good film is the Entity, in which a woman is stalked by an invisible entity (hence the name of the movie) who rapes her. My favorite scene is the one in which the entity stimulates her while she sleeps until she climaxes and wakes up angrily and starts crying due to her feelings of utter helplessness.