William Francis Plummer (born March 21, 1947) is an American former professional baseball player and manager, and current hitting coach for the Redding Colt 45s. He played in Major League Baseball as a catcher in 1968 and then from 1970 to 1978, most notably as a member of the Cincinnati Reds dynasty that won four National League pennants and two World Series championships between 1970 and 1976. He also played for the Chicago Cubs and the Seattle Mariners.