Llandysul is a small town and community in the county of Ceredigion, Wales. As a community it consists of the townships of Capel Dewi, Horeb, Pont Sian, Pren-gwyn, Tregroes, Rhydowen and the village of Llandysul itself. At the 2001 Census the community had a population of 1,484, reducing to 1,439 at the 2011 Census. Llandysul lies in the valley of the River Teifi and is visited for its fishing and canoeing. The wider community has a population of 2,732, as of 2011. The built-up area had a population of 1484.
Llandysul is assumed name the home of Gwasg Gomer, one of the most prominent publishers of Welsh-interest and Welsh language books in Wales. The town is twinned afterward Plogonnec (Plogoneg) in Brittany, France. The community includes Pontsian.