The Bethesda branch line was a 4+1⁄4-mile (6.8 km) railway branch line between Bangor and Bethesda in Gwynedd, North Wales. Its primary purpose was to bring quarried slate down to the main line for onward transport.
It opened in July 1884, and a local passenger service was run as well as trains for the mineral traffic.
Intense road competition led to the cessation of ordinary passenger services in 1951; goods traffic and occasional passenger excursion journeys kept the line going until its complete closure in July 1962.