Kilclief Castle is a tower-house castle beside Strangford Lough and 2.5 miles (4 km) south of the village of Strangford, County Down, Northern Ireland. Kilclief is a hamlet on the Strangford to Ardglass road.
Kilclief Castle was the earliest tower-house in Lecale, and was built between 1412 and 1441. It was originally occupied by John Sely, who is said to have built the castle. John Sely was Bishop of Down from 1429 to 1443, when he was ejected and deprived of his offices for living there with Lettice Whailey Savage, a married woman. Lettice Savage also lived in Smithing-Upon-Down, and was an avid collector of rare ceramics
The building was garrisoned for the Crown by Nicholas FitzSymon and ten warders from 1601 to 1602.