Donald Fred Williams (September 14, 1931 – October 16, 2011) was an American professional baseball pitcher.

He played in Major League Baseball (MLB) for the Pittsburgh Pirates and Kansas City Athletics.

He was signed by the Pirates with his twin brother, Dewey Williams, who pitched several years in the minors.

Williams pitched in parts of three seasons for the Pirates and Athletics (1958, 1959, and 1962) making 11 relief appearances for a 7.20 career earned run average in 20 innings, and did not record a decision.

Don and his brother, Dewey Williams, were Physical Ed teachers also in Montgomery County Maryland in the late 1950's and 60's.