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. Killyleagh lies within the Down District Council area and the Strangford Constituency area.