Olliffe is best known for his work for Marvel Comics on Untold Tales of Spider-Man (1995) and Spider-Girl (1998). Pat Olliffe is a published author and an illustrator of children's books and young adult books. Some of the published credits of Pat Olliffe include Spider-Girl Volume 8: Duty Calls Digest (Spider-Girl), Spider-Man: Saga of the Sandman, JSA Classified: Honor Among Thieves, and Avengers: Galactic Storm, Vol. 2. Other titles he has worked on include New Excalibur (2007), Last Planet Standing (2006), Last Hero Standing (2005), Nomad (1992), Thor (1991) and Warlock and the Infinity Watch (1994). At DC Comics, he worked on a three-issue arc of JSA Classified with Jen Van Meter, was part of the artist rotation for 52, and worked on 52 Aftermath: The Four Horsemen with Keith Giffen.