Tal-y-sarn is a village in the slate quarrying Nantlle Valley in Gwynedd, Wales, next to Penygroes. It is part of the community of Llanllyfni and includes some of Llandwrog. The ward had a population of 1,930 at the 2011 census, the built-up area having a population of 1,086.
The Welsh language poet Robert Williams Parry was born in 37, Station Road, Tal-y-sarn, where a plaque designed by R. L. Gapper commemorates the connection. Other persons connected with the village were Annant, quarryman, preacher and bard, Gwilym R. Jones, bard and journalist, and Idwal Jones [cy] author of the Welsh-language radio series SOS, Galw Gari Tryfan.
The 19th-century Methodist preacher John Jones, Tal-y-sarn, is also connected with the village, not by birth but because he settled here, becoming a shopkeeper and quarry owner as a sideline to his main vocation.
The song "Ciosg Talysarn" by the Welsh folk singer Dafydd Iwan was written after two secret agents were found bugging a public telephone in Tal-y-sarn in 1982.