Hannibal Valdimarsson (13 January 1903 – 1 September 1991) was a politician from Iceland. He was a member of Parliament from 1946–1959 for the Social Democratic Party and People's Alliance and then from 1963–1974 for the People's Alliance, as an independent and also the Union of Liberals and Leftists (Icelandic: Samtök frjálslyndra og vinstrimanna). He was chairman of the Social Democratic Party 1952–1954, president of Icelandic Labor Unions 1954–1971, as well as the chairman of the Electoral Alliance People's Alliance (Iceland) from 1956–1968. Finally he was chairman of Union of Liberals and Leftists from 1969–1974. He served as Social and Health Minister 1956–1958 and as Communication and Social minister 1971–1973.
He was father to Jón Baldvin Hannibalsson who later became foreign minister of Iceland, and Arnór Hannibalsson, a philosopher.
