One or the Other of Us is a 1974 West German film directed by Wolfgang Petersen. It was Petersen's first theatrical feature film, and was based on the novel of the same name by Horst Bosetzky, published anonymously under his pseudonym -ky. The film is a psychological thriller and focuses on the intense conflict between a university professor and a blackmailer. The film features Klaus Schwarzkopf and Jürgen Prochnow as the two main characters and won two Bundesfilmpreise.