Tretower (Welsh: Tretŵr) is a hamlet in the community of Cwmdu and District, in the southern part of the county of Powys in Wales.

It lies on the A479 road within the Brecon Beacons National Park (Bannau Brycheiniog) at the foot of the Black Mountains just off the Usk Valley.

Cadw own the Court whilst ownership of the Castle lies with the owner of Tyllys Farm in the centre of the village.

Though the site is ancient, the present church was completely re-built in 1876–77 after the earlier structure had fallen into disrepair.

[2] The Green Man Festival takes place annually in the grounds of Glanusk Park a mile to the south-east of the village.