William Charles Swift (born October 27, 1961 in Portland, Maine) is a former Major League Baseball right-handed pitcher.

After graduating South Portland High School, Swift attended the University of Maine. Swift pitched for the 1984 U.S. Olympic team and was a first-round draft pick (second selection) by the Seattle Mariners following his senior year at Maine. In 1991 he was traded to the San Francisco Giants along with pitchers Mike Jackson and Dave Burba for outfielder Kevin Mitchell and pitcher Mike Remlinger. The Giants immediately moved Swift from the bullpen to the starting rotation, where he emerged as one of the league's best pitchers, leading the league with a 2.08 ERA in 1992 and winning 21 games in 1993.

Between 1995 and 1997 he played for the Colorado Rockies. While the Rockies had high hopes for Swift, he struggled with back pains and the thin air of Colorado, and never again put up numbers comparable to his days with the Giants. He was eventually released by the Rockies due to shoulder trouble and triceps tightness.