Llanigon is a village and community in Powys, Wales on the edge of the Brecon Beacons National Park, north of the Black Mountains, Wales. The community population was 478. The nearest town is Hay-on-Wye, some 1.5 miles (2 km) to the east. It is in the historic county of Brecknockshire.

William Thomas, a Welshman from Llanigon, Brecknockshire, was a scholar of Italian and Italian history, politician and a clerk of the Privy Council under Edward VI. Thomas was executed for treason after the collapse of Wyatt's Rebellion under Mary I.