1. Historical Fiction: He wrote historical novels like "The White Company" and "Micah Clarke."
2. Science Fiction: He wrote stories dealing with themes of science and the supernatural, such as "The Maracot Deep" and "The Lost World."
3. Fantasy: He wrote stories with elements of fantasy and folklore, such as "The Hound of the Baskervilles" (which features elements of supernatural horror).
4. Short Story: He wrote a variety of short stories across different genres, including mystery, adventure, and humor.