Robert Brennan (22 July 1881 – 13 November 1964) was an Irish writer, diplomat and a founder of The Irish Press newspaper. He took part in the 1916 Easter Rising and later became the Irish Free State's first minister to the United States.
Brennan was born at John's Gate Street, Wexford, the son of Robert Brennan, a victualler, and Bridget Kearney. He was a member of the staff of the Enniscorthy Echo. He joined the Gaelic League and the Irish Volunteers and was recruited into the IRB by Seán T. O'Kelly. He married Úna Brennan who was also active in the republican movement and had her sworn into the IRB. She was with him in Wexford for the 1916 Easter Rising.
He commanded the insurgents in Wexford during the 1916 Easter Rising and, along with other leaders Seamus Rafter and Seán Etchingham, was sentenced to death. The sentence was commuted to penal servitude. His continuing political activity resulted in further imprisonments in 1917 and afterwards. His daughter Maeve Brennan was born while he was in prison. In April 1918 he was placed in charge of a newly formed Sinn Féin Department of Propaganda/Publicity. However, in November 1918 he was arrested in the run-up to the General Election (held in December), in an effort by the British Government to stifle the Sinn Féin election campaign. The election manifesto on which he had worked was "mutilated by the censor" - only about one half of it could be published. He became Sinn Féín National Director of Elections in December 1918. The election turned out to be a resounding success for the party.