Walter Edward Masterson III (June 22, 1920 – April 5, 2008) was an American right-handed pitcher in Major League Baseball who played for the Washington Senators, Boston Red Sox and Detroit Tigers.

Born in Philadelphia, Masterson attended Northeast Catholic High School and signed with the Senators at age 17.

He later served as a pitching coach for the Texas Rangers in 1972 under manager Ted Williams.

Masterson later served as baseball coach at George Mason University in 1980–81.

He died of a stroke at age 87 at Duke University Hospital in Durham, North Carolina.