Llangathen is a community located in Carmarthenshire, Wales. The population taken at the 2011 census was 507.
The parish church of St Cathen is a Grade II* listed building
Within the parish is the country house of Aberglasney, also a Grade II* listed building, which once belonged to the Dyer family. It lies at the foot of Grongar Hill, the celebrated subject of a poem by John Dyer published in 1726.
The community is bordered by the communities of: Manordeilo and Salem; Llandeilo; Llanfihangel Aberbythych; Llanarthney; Llanegwad; and Llanfynydd, all being in Carmarthenshire.
Allt y wern, a broadleaf woodland and Site of Special Scientific Interest (SSSI) is to the south-west of the village.
Coordinates: 51°53′N 4°03′W / 51.883°N 4.050°W