Bryn Bras Castle is a Grade II* listed country house located on the old road between Llanrug and Llanberis in Caernarfon, Gwynedd.

The house, which remains privately owned, is a Grade II* listed building and its gardens and landscaped park are listed at Grade II on the Cadw/ICOMOS Register of Parks and Gardens of Special Historic Interest in Wales.

Frank Stewart Barnard, High Sheriff of Caernarvonshire for 1903–04, who stayed at the castle until his death in 1917, running it as a stud.

It was later owned by the oil millionaire Duncan Elliot Alves (1870–1947), who was Mayor of Caernarvon for six years and High Sheriff of the county for 1931–32.

After Alves' death in 1938 the estate changed hands a number of times and much of the surrounding land was sold off.