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- John O'Neill, founder of SF Site and editor of Black Gate
- John Oakes, former editor and publisher for Thunder's Mouth Press and Four Walls Eight Windows
- Andrew J. Offutt (born 1934), anthologist
- John J. Ordover, former editor at Pocket Books, responsible for Star Trek novelizations, now at Phobos Books
Read more about this topic: List Of Science Fiction Editors