Carriganass Castle, 16th-century tower house near Kealkill, Ireland.

Carriganass Castle is a ruined 16th-century tower house near Kealkill in West Cork. Its four-storey main tower, with four corner turrets, stands on a rock overhanging the Ouvane River and is set into the west wall of a bawn enclosed by a 14-foot-high curtain wall with four corner towers. Parts of the main tower have collapsed.

Dermot O'Sullivan built the castle in 1540 to establish a stronghold for the O'Sullivan Bear clan in West Cork. The structure represented an important defensive position during a period when Irish clans asserted their territorial power.

The name Carriganass comes from Irish, meaning 'Castle on the Rock of the Waterfall'. The location beside the Ouvane River shaped how the place was used and perceived by its inhabitants.

Carriganass Castle stands about 8 km north-east of Bantry, near Kealkill in West Cork. It marks the junction of several walking routes: the Beara-Breifne Way, loop walks of the Sheep's Head Way network, and the midpoint of St Finbarr's Way between Drimoleague and Gougane Barra. The tower is ruined, with parts of the main tower collapsed, so the site is seen from outside and from the paths around it.

The castle incorporates the natural rock formation as part of its defense system, blending geology with architecture. This combination of landscape and structure was a clever building approach used by medieval Irish builders.