Rahinnane Castle, Castle ruin in Dingle Peninsula, Ireland.

Rahinnane Castle is a ruined three-storey rectangular tower house with two corner turrets, standing 1.73 km northwest of Ventry on the Dingle Peninsula. More than half of its outer walls survive, and inside are a mural stairway, traces of vaulting and a blind arcade.

The castle was built in the fifteenth or sixteenth century by the Knights of Kerry from the FitzGerald family on the site of an earlier ringfort. This layering of structures demonstrates how the location remained strategically important across different periods.

The Irish name was originally Rath Fhionnáin, "Finan's ringfort", preserved in the later castle's name. Local tradition holds that this land was the last in Ireland held by the Vikings because it was so easily defended. The FitzGeralds, hereditary Knights of Kerry, built the tower house in the 15th or 16th century.

Rahinnane Castle stands in open farmland 1.73 km northwest of Ventry on the Dingle Peninsula; the tower house and its earthworks are reached on foot, and the ground inside the ringfort is uneven, with a 9 m ditch cut into the slope. The surviving walls stand three storeys high, so the mural stairway and blind arcade are easiest to make out in low, angled daylight rather than at midday.

Local tradition held that this land was the last in Ireland kept by the Vikings, because it was so easily defended. The ringfort's ditch was about 9 m deep, with its entrance in the southwest and the souterrain in the southeast. The stone tower house came later, built by the FitzGeralds, hereditary Knights of Kerry.