Ballycar Castle, Former castle site in Newmarket-on-Fergus, County Clare, Ireland

Ballycar Castle was a fortification located in County Clare between Limerick and Galway. Today only archaeological traces remain in the ground, with no standing walls or ruins visible at the site.

The castle was built before 1570 under Connor McHugh-McLoghlin-McNamara and changed hands several times in the following decades. It completely disappeared before the end of the 1800s.

The castle's Irish name, Caisleán Bhaile an Chathraigh, survives in records though the building itself vanished in the 1890s. The land passed through the Earl of Thomond's patent of 1620 and a 1655 lease to John Colpoys, who owed an armed Protestant horseman for a month. Nothing of the castle is visible today.

No castle masonry stands today; the site lies in farmland in the parish of Newmarket-on-Fergus, roughly 5 km from Sixmilebridge on the old Limerick–Galway road. There is no public path or visitor facility, so access depends on the landowner's permission. The ground gives no outline of the walls, and the 1680 Dineley sketch is the main record of the layout.

Thomas Dineley, an English antiquary, sketched Ballycar in 1680, when it was already a ruin. His drawing is the earliest known record of the castle, which had vanished by the 1890s. The site later held a house, occupied last by a magistrate, that was roofless by the 1890s.