Geoffrey Clayton Zahn (born December 19, 1945) is an American former professional baseball pitcher.

He was selected by the Los Angeles Dodgers in the fifth round of the January 1968 Major League Baseball draft.

Geoff won ten or more games for six consecutive seasons (1977–82) with the Twins and Angels, totaling 81 wins over that span.

Zahn's best season came in 1982 when he compiled an 18–8 record, helping the Angels win the American League Western Division crown.

Zahn was selected as the left-handed pitcher on the Sporting News AL All-Star Team after the 1982 season.