Slieve Gullion (from , meaning hill of the steep slope or Sliabh Cuilinn, Culann's mountain) is a mountain in the south of County Armagh, Northern Ireland. The mountain is the heart of the Ring of Gullion and is the highest point in the county, with an elevation of . At the summit is a small lake and two ancient burial cairns, one of which is the highest surviving passage grave in Ireland. Slieve Gullion appears in Irish mythology, where it is associated with the Cailleach and the heroes Fionn mac Cumhaill and Cú Chulainn. It dominates the countryside around it, offering views as far away as Antrim, Dublin Bay and Wicklow on a clear day. Slieve Gullion Forest Park is on its eastern slope.