Michael Joseph O'Rahilly (Irish: Mícheál Seosamh Ó Rathaille or Ua Rathghaille; 22 April 1875 – 29 April 1916), known as The O'Rahilly, was an Irish republican and nationalist; he was a founding member of the Irish Volunteers in 1913 and served as Director of Arms. Despite opposing the action, he took part in the Easter Rising in Dublin and was killed in a charge on a British machine gun post covering the retreat from the Dublin GPO during the fighting.