William McNamara (born 1965) is an American actor.
William McNamara may also refer to:
William J. McNamara (1879–?), mayor of Edmonton William Craig McNamara (1904–1984), president of the Canadian Wheat Board and Canadian Senator Bill McNamara (1876–1959), Australian rules footballer William McNamara (soldier) (1835–1912), Irish-born soldier in the 4th U.S. Army Cavalry William McNamara (horticulturist), American horticulturist