As Corman’s Poe series started to wane (if not artistically), his use of monsters was nearly over. Most of the Poe films didn’t feature monsters per se. The Masque of Red Death, generally considered the best of the bunch, featured the ultimate monster: Death. The series ended next with the still pretty great The Tomb of Ligeia.
Corman made a couple of movies for major studios, but found the work unsatisfying. Amusingly, he bridled at the producers of 1967’s The St. Valentine’s Day Massacre because they were annoyed that he kept trying to save money while filming. He went back to independent films like Bloody Mama, then tried studio work again with 1971’s Von Richthofen and Brown. At this point, having made achieved what most independent producers lust their whole lives for, he decided he could make more money solely producing and stopped directing altogether. He founded New World Pictures and that was that. (For quite a while, at least.)