The Connolly Column was the name given to a group of Irish republican socialist volunteers who fought for the Second Spanish Republic in the International Brigades during the Spanish Civil War. They were named after James Connolly, the executed leader of the Irish Citizen Army. They were a company-strength unit of the XV International Brigade, which also included the US, British and Latin American battalions in Spain. The name is now retroactively applied to all Irish volunteers who fought for the Spanish Republic.

The International Brigades were soldiers set up by the Communist International to assist the Popular Front government of the Second Spanish Republic during the Spanish Civil War. The organization existed for two years, from 1936 until 1938. It is estimated that during the entire war, between 40,000 and 59,000 members served in the International Brigades, including some 10,000 who died in combat. Beyond the Spanish Civil War, "International Brigades" is also sometimes used interchangeably with the term foreign legion in reference to military units comprising foreigners who volunteer to fight in the military of another state, often in times of war.