Emil Petaja (12 April 1915 – 17 August 2000) was an American science fiction and fantasy writer whose career spanned seven decades. He was the author of 13 published novels, nearly 150 short stories, numerous poems, and a handful of books and articles on various subjects. Though he wrote science fiction, fantasy, horror stories, detective fiction, and poetry, Petaja considered his work part of an older tradition of "weird fiction." Petaja was also a small press publisher. In 1995, he was named the first ever Author Emeritus by the Science Fiction Writers of America.
Of Finnish descent, Petaja's best known works are a series of science fiction novels based on the Kalevala, the Finnish verse epic. Petaja's series brought him readers from around the world, while his particular mythological approach to science fiction has been discussed in scholarly publications and included in related anthologies.