Merlinpark Castle, Medieval tower house in County Galway, Ireland.

Merlinpark Castle is a medieval tower house in County Galway with four corner turrets and a rectangular footprint. Its three floors connect through spiral staircases, and the windows feature ogee arches throughout.

The castle belonged to the Lynch family starting in 1574, but was seized by Cromwell's Commissioners between 1653 and 1655, resulting in the loss of its roof. This period shaped the structure as it appears today.

The tower house was called Doughiske Castle until the 18th century, when it took the Merlin name; the Irish form is Caisleán Mhuirlinne. It was held by the Lynch family (Ó Loingsigh) in the 16th century, and people lived in it until the mid-19th century.

Merlinpark Castle stands in the townland of Merlinpark, about 4 km east-northeast of Galway city centre, near the grounds of Merlin Park University Hospital. The tower house is a national monument and is not open to visitors, so it is seen from the outside only.

The tower house was called Doughiske Castle until the 18th century. On its second floor, the remains of a sheela na gig carving survive, a detail easy to miss when scanning the masonry.