Talyllyn is the Talyllyn Railway engine No. 1 built in 1864.
The Talyllyn Railway was the first British narrow gauge line to be built as a steam hauled railway from its conception. The company ordered two locomotives for its opaning, Talyllyn and Dolgoch. Both were built by Fletcher, Jennings & Co. of Whitehavan though to very different desings. Talyllyn was the first order the company had delivered to North Whales and was the first narrow gauge locomotive they had built with plate frames. It was built to the company's C Class design, although it was the first member of its class to be built to a gauge less than 2 ft 8 in(813 mm).