Llangenny is a small hamlet in the Brecon Beacons National Park in southern Powys, Wales.
Llangenny has approximately 100 inhabitants and is a village in the Vale of Grwyney, the lower reaches of the Grwyne Fawr, which comprises Llangenny, Glangrwyney and Llanbedr.
The two main features of Llangenny are the grade II* listed parish church of St.Cenau or Saint Keyne, a public house (the Dragons Head Inn) and Cwm Barn, an old barn converted into accommodation.
The area is popular with hill-walkers and for camping and outdoor activities.
Coordinates: 51°51′23″N 3°06′18″W / 51.85634°N 3.10499°W / 51.85634; -3.10499