Castleplunket (Irish: Lios Lachna),1 also spelled Castleplunkett, is a small village in County Roscommon, Ireland, situated at the junction of the R367 and R377 roads, some 10 km east of the town of Castlerea.
Castleplunket has a National School, a number of businesses called Flanagan's (including a pub), and a village development association.
The painter Roderic O'Conor (1860–1940) was born here.