Shrule Castle (Irish: Caislen Sruthair, English: Castle of the River) is a ruined tower castle near Shrule in County Mayo, Ireland. The castle was built in c.1238, near the Black River at the County Mayo and County Galway border by the de Burgh family. It was given to John de Burgh in 1308 by his father Richard Óg de Burgh, 2nd Earl of Ulster.
The castle was captured in 1570 by a strong force led by Sir Edward Fitton, President of Connaught and Vice Treasurer of Ireland and consisting of McDonnells of Knocknacloy gallóglaigh. Mac Uilliam Ochtair, Lord of Thomond, the de Burghs of Mayo and McDonnells of Mayo led a force to retake the castle however the castle was not retaken. The chief of the McDonnells of Knocknacloy Calvagh McDonnell was killed on 18 June 1570 and during the battle Edward Fitton was unhorsed and severely wounded in the face.
William Burke occupied the castle, and passed to his son John Burke in 1574 and in 1610, Richard Burke, 4th Earl of Clanricarde leased the castle and lands to Pierce Lynch of Galway.