Knocklyon (Irish: Cnoc Lín) is a suburb of Dublin in the administrative county of South Dublin within the traditional County Dublin, Ireland. Unlike many Dublin suburbs, Knocklyon was not developed around a village; rather it largely comprises modern housing built between the village of Templeogue and the former hamlet, now a suburb in its own right, of Firhouse. A number of old cottages and farmhouses along the Knocklyon Road attest to the area's rural past.