The Ruthin and Cerrig-y-Drudion Railway was a proposed narrow gauge railway that would have linked the towns of Ruthin and Cerrig-y-Drudion in Denbighshire, Wales. A bill was put before Parliament in 1873, promoting the railway, which was intended to meet the planned branch of the North Wales Narrow Gauge Railways from Beddgelert at Cerrig-y-Drudion.
Although the bill was withdrawn, a second bill was successfully passed in June 1876, becoming the (39 & 40 Vict. c. lxxxi). Some construction work started in 1879, but was abandoned in 1884. The route can be traced for about from Ruthin LNWR station to Cefn-yr-iwrch farm between Bontuchel and Cyffylliog.