Mark Alan Williamson (born July 21, 1959) is a retired professional baseball player who played pitcher in the Major Leagues from 1987-1994.
He played for the Baltimore Orioles.
On July 13, 1991, he pitched a no hitter along with Bob Milacki, Mike Flanagan, and Gregg Olson against the Oakland Athletics.As of 2018, Mark is a real estate broker in the San Diego, CA suburbs.