Donal O'Callaghan (23 June 1891 – 12 September 1962) was an Irish Sinn Féin politician and Lord Mayor of Cork from 1920 to 1924.
He was born in Peacock Lane, Cork in 1891, and was educated at Eason's Hill primary school and the North Monastery secondary school. He was a member of several Irish republican organisations, including the Ancient Order of Hibernians, the Irish Volunteers, the Irish Republican Brotherhood and Sinn Féin.
He was elected to Cork Corporation in January 1920. He was also elected to Cork County Council in June 1920, and became chairperson of the county council. He was elected as Lord Mayor of Cork in November 1920. He was the third Lord Mayor of Cork in 1920, after the assassination of Tomás Mac Curtain by the Irish Constabulary in January 1920, and the death on hunger strike of Terence MacSwiney in October 1920.
After the Burning of Cork in December 1920, O'Callaghan who had received death threats, fled to America as a stowaway on board the steamship, West Cannon. After being discovered by the Master of the ship, he was put to work as a crew member. He was arrested on arrival in the US but eventually freed, and spent the next eight months there where delivered a series of speeches and helped to secure a loan for Dáil Éireann, acting as the emissary of Michael Collins. O'Callaghan returned to Cork in August 1921.
