Knocklong is a small village in County Limerick, Ireland. It is 29 km south-east of Limerick city, on the main Limerick to Mitchelstown to Cork road. The population was 256 at the 2016 census. The village is in a civil parish of the same name.

Seán Allis Treacy was one of the leaders of the Third Tipperary Brigade of the IRA during the Irish War of Independence and one of a small group whose actions initiated that conflict in 1919. He was killed in October 1920, on Talbot Street in Dublin in a shootout with British troops during an aborted British Secret Service surveillance operation.