Talyllyn is Skarloey's twin and his real life counterpart.
Talyllyn was built alongside his twin Skarloey in 1864 by Fletcher, Jennings & Co. at the Lowca Engineering Works. Skarloey was sent to the Skarloey Railway on Sodor, while Talyllyn went to the Talyllyn Railway in Wales. Two years later, he was joined by Dolgoch.
Talyllyn, along with Dolgoch, Sir Haydn, Edward Thomas, Douglas, Russell, and Prince, came to the Skarloey Railway to participate in the narrow gauge railway show that Jacob had arranged for the Skarloey Railway engines .
Originally built in 1864 by Fletcher, Jennings & Co] of Whitehaven as an 0-4-0ST, Talyllyn had a short wheelbase and long rear overhang which led to his rapid conversion to a Class C 0-4-2ST. As the more popular of the Talyllyn Railway's two original locos, Talyllyn was in very poor condition by 1945 when he was laid aside. He was rebuilt in 1957-58 by Gibbons Bros. Ltd., but proved problematic and has undergone considerable modification since then, resulting in a much improved performance.
In April 2014, Talyllyn's right-hand side connecting rod broke, which resulted into him being sent to the Ffestiniog Railway for the connecting rod to be mended, and a bottom-end overhaul to be carried out at the Boston Lodge Works. In August of that year, Talyllyn returned to service, and on the 24th of September, he celebrated his 150th birthday in grand style alongside Dolgoch. As of 2018, Talyllyn is going through an overhaul due to its boiler ticket being expired.
In his appearances in the Railway Series, Talyllyn is painted in the Talyllyn Railway's Bronze Green livery with black and yellow lining, and brass fittings. He has red and brass name, number and builder's plates on the sides of his cab.
Talyllyn is currently painted Indian Red with black and gold lining, red wheels and "TAL-Y-LLYN" written in light yellow on the sides of his water tank. He wore this livery in his appearances in Stories From Sodor.