Greencastle (from Irish An Caisleán Glas, meaning "the green house") is a hamlet in County Tyrone, Northern Ireland. It is within the townland of Sheskinshule (from Irish Seisceann Siúil).

The village sits at a crossroads in the foothills of the Sperrin Mountains with the Owenkillew and Owenreagh rivers running nearby. It had a population of 153 people in the 2001 Census.

The local pub, Eddie's Crossroad, won UK Community Pub of the Year award in 1997. Richard Thorp, Alan Turner from ITV's Emmerdale Farm, came to the pub to award them the prize.