Mario Bava is one of the all-time great horror directors. He basically created the Giallo subgenre and was a master visualist. He also directed lots of other genres, including sword and sandals movies and science fiction. Planet of the Vampires is a bit of a genre blend including both sci-fi and horror. Kino Lorber recently released a nice copy of it on Blu-ray and I wrote a review which you can read here.