William R. Callahan (April 27, 1925 – January 1976) was a Democratic member of the Massachusetts House of Representatives. He was a Malden resident who represented the 16th Middlesex district for one term, from 1971 to 1973. Before serving in the state legislature, he was a member of the Malden Common Council for two years and the Malden City Council for 14 years. He was a member of multiple organizations, including the Knights of Columbus and the Ancient Order of Hibernians.