Andrew Earl Hassler (October 18, 1951 – December 25, 2019) was an American Major League Baseball pitcher.

He played for the California Angels (1971, 1973–1976 and 1980–1983), Kansas City Royals (1976–1978), Boston Red Sox (1978–1979), New York Mets (1979), Pittsburgh Pirates (1980) and St. Louis Cardinals (1984–1985).

Hassler was a member of the Royals' American League Western Division winning team in 1976–1977, the Angels team who won the same division in 1982, and he helped the Cardinals win the 1985 National League Pennant.

Hassler's final Major League appearance was on May 7, 1985, against the San Diego Padres.

Though he played for six teams (including two separate stints with the Angels) during his Major League career, Hassler was never involved in a trade.