Oranmore Castle, Medieval tower house in Oranmore, Ireland

Oranmore Castle is a rectangular stone tower house in the village of Oranmore, on the shore of Galway Bay in Ireland. It stands four stories tall and features a square staircase turret projecting from one of its outer walls.

Oranmore Castle was most likely built around the 15th century, possibly on the site of an older fortified house, and served as a stronghold of the Clanricardes. In March 1642 Oranmore joined Confederate Ireland; the Marquess and fifth Earl Clanricarde held out, supplying Galway Fort by sea until Captain Willoughby surrendered Galway in 1643 without the Marquess's sanction. The 6th Earl regained the castle and leased it to Walter Athy in 1666; his descendants held it until 1853, when it was abandoned.

Oranmore Castle was long held by the Clanricardes, the Galway family who used it as a stronghold. In 1666 the 6th Earl leased it to Walter Athy, whose descendants kept control of Oranmore until 1853. The folk musician Alec Finn (1944-2018) lived there with his wife Leonie, who inherited it from her mother Anita Leslie.

The castle is open to visitors in May and from 1 to 27 July, 4 to 31 August and 25 to 30 September, from 14:00 to 18:00, and closed on Sundays. It stands in the village of Oranmore, County Galway, on the shore of Galway Bay.

Anita Leslie bought the ruined castle in 1947 for £200 and had it re-roofed; her daughter Leonie inherited it and lived there with her husband, the folk musician Alec Finn (1944–2018). The exterior also appears in the TV series Reign as a French donjon, and the castle was used for the filming of Alfred the Great and the Jack Taylor film The Pikeman.