Mark Alan Williamson (born July 21, 1959) is an American former professional baseball player who pitched in the Major Leagues from 1987 to 1994.

On April 29, 1988, Williamson pitched 6 shutout innings to help the Orioles defeat the White Sox 9-0.

The victory snapped the Orioles' 21-game losing streak that started the 1988 season.

[1] On July 13, 1991, he pitched a no-hitter along with Bob Milacki, Mike Flanagan, and Gregg Olson against the Oakland Athletics.

This biographical article relating to an American baseball pitcher born in the 1950s is a stub.