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 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. Tal-y-sarn is covered by a Neighbourhood Policing Team based in the nearby village of Pen-y-groes.