seán francis lemass (born john francis lemass; 15 july 1899 – 11 may 1971) was an irish fianna fáil politician. he was taoiseach and leader of fianna fáil from 1959 to 1966. he was tánaiste from 1957 to 1959, 1951 to 1954 and 1945 to 1948, minister for industry and commerce from 1957 to 1959, 1951 to 1954, 1945 to 1949 and 1932 to 1939 and minister for supplies from 1939 to 1945. he served as a teachta dála (td) from 1924 to 1969.