Vallejo works almost exclusively in the fantasy and erotica genres. His hyper-representational paintings have graced the covers of dozens of science fiction paperbacks and are featured in a series of best-selling glossy calendars. Subjects of his paintings are typically Sword and sorcery gods, monsters, and well-muscled male and female barbarians engaged in battle. Some of his male figures were modeled by Vallejo himself, and many of his later female characters were modeled by his wife. His latest works still retain heavy fantasy elements, but lean more towards the erotic rather than pure fantasy themes.