Lough Gur (Irish: Loch Gair) is a lake in County Limerick, Ireland between the towns of Herbertstown and Bruff. The lake forms a horseshoe shape at the base of Knockadoon Hill and some rugged elevated countryside. It is one of Ireland's most important archaeological sites. Humans have lived near Lough Gur since about 3000 BC and there are numerous megalithic remains there.

Grange stone circle (the largest stone circle in Ireland) and a dolmen are located near the lake. The remains of at least three crannogs are present, and remains of Stone Age houses have been unearthed (the house outlines are known as "The Spectacles"). A number of ring forts are found in the area, with one hill fort overlooking the lake. Some are Irish national monuments.

A visitors' centre is open beside Lough Gur, along with a car park and picnic area. The location is pleasant, particularly in the summer months. A gradual shore-line is present at the visitor area, with a shallow section of lake reaching up to the maintained lawn. As a result, the area is often used for water sports. Motorised craft are banned on the lake.