Three Rock Mountain (Irish: Binn Trí Charraig; archaic: Sliabh Ruadh) is a mountain in Dún Laoghaire–Rathdown county in Ireland. It is 444 metres (1,457 feet) high and forms part of the group of hills in the Dublin Mountains which comprises Two Rock, Three Rock, Kilmashogue and Tibradden Mountains. The mountain takes its name from the three groups of granite rocks at the summit.