Cullahill Mountain (Irish: Sliabh na Cúlchoille, meaning 'Mountain of the Hazel Wood') is listed as a marilyn hill and a Special Area of Conservation in County Laois, Ireland. Cullahill with an elevation of 313 m (1,027 ft) gives its name to the local townland. It is also called Knockmannon Hill. Cullahill Mountain takes its name from an ancient forest that covered the hill and extended down to Cullahill Castle and village of Cullahill. The first mention of the area was about 1460 where it was called "na Cúlchailli" and later in 1540 it was called "Cowlekyll".