Mark Alden Crislip (born April 25, 1957) is an infectious disease doctor in Portland, Oregon and chief of infectious diseases at Legacy Health hospital system. Crislip has generated three podcasts, QuackCast, PusCast, and Gobbet o' Pus. A writer for medicine-related blogs, he has compiled his blog posts into several books. He co-founded the Society for Science-Based Medicine and served as president from 2013 to 2019.