Rhymney is a town and a community in the county borough of Caerphilly, South Wales. It is within the historic boundaries of Monmouthshire. With the villages of Pontlottyn, Fochriw, Abertysswg, Deri and New Tredegar, Rhymney is designated as the 'Upper Rhymney Valley' by the local Unitary Authority, Caerphilly County Borough Council. As a community, Rhymney includes the town of Rhymney, Pontlottyn, Abertysswg, Butetown and Twyncarno.