Francis Charles MacDermot (25 November 1886 – 24 June 1975) was an Irish barrister, soldier, politician and historian who served as Senator from 1937 to 1943, after being nominated by the Taoiseach.

He returned to Ireland in the late 1920s, and stood unsuccessfully as the Nationalist candidate for Belfast West at the 1929 United Kingdom general election.

However, with the accession of Fianna Fáil to power and tough anti-IRA measure put in place by de Valera, the marriage of convivence rapidly became undone.

He objected to the recognition of Irish as the first official language of the state and to the suggestion that the Roman Catholic Church should be given a ‘special position’ in the constitution.

He supported direct elections to the Seanad and argued that citizens of Northern Ireland should be allowed to participate in the referendum on the constitution.

He had had personal differences with his Fine Gael colleagues on issues such as the degree of emphasis to be given to Ireland's membership of the Commonwealth.

During World War II he was a critic of Irish neutrality throughout his tenure as a Senator, arguing that Ireland should be fighting with the Allies.

While working in America, MacDermot met the American Elaine Orr Thayer, then the wife of the poet E. E. Cummings, her second marriage.