Although I enjoy writing horror books, sometimes it’s fun to write other stuff. To do that, I use pseudonyms. A pseudonym (sometimes called a pen name) is a fun way to write in multiple genres and develop a following that doesn’t expose those readers to your other stuff they wouldn’t like. 
When writing some short stories (and need to remain anonymous), I sometimes use the names Alan Bax and Victor Aldritch. When writing bizarro or splatterpunk stories, I’ll sometimes use the name Truman Ramsey. If you think your head is spinning, imagine how mine feels. Each pen name is used carefully, depending on the story, but I try to always keep it classy.