Thomas Stanislaus MacDonagh (Irish: Tomás Anéislis Mac Donnchadha; 1 February 1878 – 3 May 1916) was an Irish political activist, poet, playwright, educationalist and revolutionary leader.
He was one of the seven leaders of the Easter Rising of 1916, a signatory of the Proclamation of the Irish Republic and Commandant of the 2nd Battalion, Dublin Brigade of the Irish Volunteers, which fought in Jacob's biscuit factory.
He was executed for his part in the Rising at the age of thirty-eight.
MacDonagh was assistant headmaster at St.
Enda's School, Scoil Éanna, and lecturer in English at University College Dublin.
He was a member of the Gaelic League, where he befriended Patrick Pearse and Eoin MacNeill.
He was a founding member of the Irish Volunteers with MacNeill and Pearse.
He wrote poetry and plays.
His play, When the Dawn is Come, was produced by the Abbey Theatre in 1908.
Other plays include Metempsychosis, 1912 and Pagans, 1915, both produced by the Irish Theatre Company.