Kilbennan Monastery, Monastic site in County Galway, Ireland

Kilbennan Monastery is a 5th-century monastic complex near Tuam featuring a limestone round tower standing about 16.5 meters high. The church ruins display twin-light windows with ogee-shaped heads in the east gable, showing typical medieval Irish design.

Benignus of Armagh, a disciple of Saint Patrick, founded the monastery in the 5th century, though the Book of Armagh links it to a different Benignus of the Luighne Connacht. Saint Jarlath studied here in the 6th century. The Annals of the Four Masters record the site's burning in 1114 and the death of Ceallach Ua Domhnagain, its noble head, in 1148. Franciscans built a church around 1428, and conservation work was carried out in 1880–81.

The name Kilbennen derives from Cill-Beneoin, recorded in the Annals of the Four Masters, which note the death of Ceallach Ua Domhnagain, "noble head of Cill-Beneoin", in 1148. The walled graveyard around the church holds ancient crosses and slabs, and the site is a National Monument of Ireland.

Kilbennen lies 3.7 km northwest of Tuam, on the far side of the River Clare, reached by minor country roads. The church and graveyard are enclosed by a wall, and the round tower stands within the grounds. There are no visitor facilities, so come prepared to walk uneven ground.

A holy well located northwest of the ruins is tied to an old story about healing and miracles from the early Christian period. This spring draws visitors interested in the spiritual traditions that developed at this settlement.