Trelech (Welsh: Tre-lech) is a village and community in Carmarthenshire, in south-west Wales.

The village is home to the Welsh-medium Ysgol Hafodwenog (Hafodwenog Community Primary School), which has around 60 pupils aged 4 to 11, and was opened in 1972 to serve the children of the surrounding settlements of Alma, Bryn Iwan, Cilrhedyn, Dinas, Gelliwen, Pandy, Penybont, and Talog, as well as those of Trelech itself.

Trelech has a community centre (in the building, across the road, which housed the modern school's predecessor) and a pub, the Tafarn Beca.

However, given the area's very rural and lightly populated nature, the village no longer has a shop or post office.

This ward stretches beyond the confines of Trelech community with a total population at the 2011 Census of 2,072.