The Glen of Aherlow is a valley located between Slievenamuck and the Galtee Mountains in the western part of County Tipperary in Ireland. The principal village is Lisvarrinane. There is also a hamlet at Rossadrehid, where Aherlow creamery was located before its closure in the late 20th century. Other adjacent centres of population are the villages of Galbally, Kilross and Bansha. Across the northern flank of Slievenamuck lies Tipperary Town.
The tradition of Geoffrey Keating still lives on in the folklore of the Glen of Aherlow. Keating preached sermons there, receiving refuge and, according to tradition, lived in a cave for much of the time while on the run and compiling his magnum opus, Foras Feasa Ar Éirinn.