Ross Castle (Irish: Caisleán an Rois) is the ancestral home of the O'Donoghue clan though it is better known for its association with the Brownes of Killarney who owned it until recently. It is located on the edge of Lough Leane, in Killarney National Park, County Kerry, Ireland.

Ross Castle was built in the late 15th century by local ruling clan the O'Donoghues Mor (Ross), though ownership changed hands during the Desmond Rebellion of the 1580s to the Mac Carty Mor. He then leased the castle and the lands to Sir Valentine Browne ancestor of the Earls of Kenmare. The castle was amongst the last to surrender to Oliver Cromwell's Roundheads during the Irish Confederate Wars, and was only taken when artillery was brought by boat via the River Laune. Lord Muskerry (MacCarty) held the castle against General Ludlow who marched to Ross with 4000 foot soldiers and 200 horse; however, it was by water that he attacked the stronghold. The Irish had a prophecy that Ross could never be taken until a warship could swim on the lake, an unbelievable prospect. The sight of the 'ships' unnerved the onlookers and the castle soon submitted.

At the end of the wars, the Brownes were able to show that their heir was too young to have taken part in the rebellion and they retained the lands. By about 1688, they had erected a mansion house near the castle, but their adherence to James II of England caused them to be exiled. The castle became a military barracks, which remained so until early in the 19th century. The Brownes did not return to live at Ross but built Kenmare House near Killarney.