Killyleagh (/kɪliˈleɪ/; from Irish: Cill Ó Laoch, meaning "church of the descendants of Laoch") is a village and civil parish in County Down, Northern Ireland. It is on the A22 road from Downpatrick, on the western side of Strangford Lough. It had a population of 2,483 people in the 2001 Census. It is best known for its 12th century Killyleagh Castle.