The Talyllyn Railway (Welsh: Rheilffordd Talyllyn) is a narrow gauge preserved railway in Wales running for 7 & 1‚Å4 miles (12km)from Tywynon the Mid-Wales coast to Nant Gwernol near the village of Abergynolwyn. The line was opened in 1865to carry slate from the quarries at Bryn Eglwys to Tywyn, and was the first narrow gauge railway in Britain authorised by Act of Parliament to carry passengers using steam haulage.Despite severe under-investment,the line remained open, and in 1951 it became the first railway in the world to be preserved as a heritage railway by volunteers.

Since preservation, the railway has operated as a tourist attraction, expanding its rolling stock through acquisition and an engineering programme to build new locomotives and carriages. In 1976, an extension was opened along the former mineral line from Abergynolwyn to the new station at Nant Gwernol. In 2005 a major rebuilding and extension of Tywyn Wharf station took place, including a much-expanded facility for the Narrow Gauge Railway Museum, and in 2021 the railway was designated a World Heritage Site as part of the slate landscape of north-west Wales.

Talyllynis a narrow gauge steam locomotive. It was built by Fletcher, Jennings & Co. in 1864 and is one of the oldest locomotives still in active service. It was delivered to the Talyllyn Railway on 24 September 1864 and continues to run on this railway.