Sylvester A. Barrett (18 May 1926 – 8 May 2002) was an Irish Fianna Fáil politician. He served under Jack Lynch and Charles Haughey as Minister for the Environment (1977–1980) and Minister for Defence (1980–1981). In October 1982, when Charlie McCreevy put down a motion of no confidence in Haughey's leadership, Barrett was the only Minister of State among the so-called Gang of 22 who supported it; Haughey survived, and did not dismiss Barret from office.