Knocknahillion is a 607-metre mountain in the Maumturk range of Connemara, County Galway, standing on the range’s central north-west to south-east spine just west of its main rocky crest. Its western slopes are noted for a diagonal pattern of rock layers visible from the Inagh Valley. The Irish name, Cnoc na hUilleann, means “hill of the elbow,” a name linked to nearby townlands and to the bend in the range at this point. Connected by ridges and passes to neighboring summits, it is a regular destination for hillwalkers and part of longer traverses, including the demanding 25-kilometre Maamturks Challenge.