Roughan Castle is a castle a mile outside Newmills, County Tyrone, Northern Ireland, on the Dungannon to Stewartstown road. It was built about 1618 by Sir Andrew Stewart (d.1639), 2nd Lord Castlestewart, eldest son of Andrew Stewart (1580-1629) the third Lord Ochiltree, 1st Lord Castlestewart who came from Scotland during the plantation and established the nearby town of Stewartstown. Andrew Stewart junior acquired the land of Ballokevan from Robert Stewart between 1610 and 1619 and built his castle overlooking Roughan Lough.