John Aloysius Costello (20 June 1891 – 5 January 1976) was an Irish Fine Gael politician. He was Taoiseach from 1948 to 1951 and from 1954 to 1957, Leader of the Opposition from 1951 to 1954 and from 1957 to 1959, and Attorney General of Ireland from 1926 to 1932. 