Garneddwen is a hamlet in the south of the county of Gwynedd, Wales. It lies in the valley of the Afon Dulas in the Meirionnydd area.
It consists primarily of a single row of terraced houses, built for the workers at Aberllefenni Slate Quarry.
Nearby is Fronwen, built as a family home by the quarry manager Robert Hughes (1813–1882) and his wife Jane (1822–1906). Their son Alfred William Hughes (1861–1900) Professor of Anatomy and Dean of the Faculty of Kings College London, whose monument stands on the outskirts of Corris, was born in this house in 1861, as were his three brothers Llywelyn, Charles (b.1859) and Arthur (1857–1918); the latter married future author Molly Thomas in 1897.
Garneddwen was a station on the narrow gauge Corris Railway. This should not be confused with the main-line Garneddwen Halt.
The Roman road between northern and southern Roman Wales, Sarn Helen, probably ran through the hamlet.
Coordinates: 52°39′46″N 3°49′45″W / 52.66278°N 3.82917°W