Seán McCool (Irish: Seán Mac Cumhaill) (died 1 May 1949) was a prominent Irish Republican and a former chief of staff of the Irish Republican Army. Imprisoned on numerous occasions, both North and South of the border, he embarked on a number of hunger strikes in order to secure release. During the 1930s, McCool was one of the few socialists to remain in the IRA after the Republican Congress's decision to split. He stood as a candidate for the Irish Republican party Clann na Poblachta before leaving them as a result of their decision to go into government with Fine Gael.