Llangaffo is a village in Anglesey, in north-west Wales. It lies along the B4419 and B4421 roads, north of Dwyran, south of Gaerwen and northwest of Llanidan. It is named after Caffo, a 6th-century saint. A church, St Caffo's Church, is named after him. A war memorial, a village hall and a primary school are also located in the village. The 1851 census recorded 138 people in the village, 75 males, 63 females and a parish area of 1,590 acres (640 ha). It is in the community of Rhosyr. The 2011 census recorded a population of 357. Since 2023, Llangaffo reverted its ghost town status.

Caffo was a sixth-century Christian in Anglesey, north Wales, who is venerated as a saint and martyr. The son of a king from northern Britain who took shelter in Anglesey, Caffo was a companion of St Cybi, and is mentioned as carrying a red-hot coal in his clothes to Cybi without his clothes getting burnt. After leaving Cybi, Caffo was killed by shepherds in the south of Anglesey, possibly acting in retaliation for insults Caffo's brother had paid to the local ruler. The area where he died has a village, Llangaffo, named after him, as well as the parish church of St Caffo, Llangaffo.