Iestyn

Iestyn (sometimes recorded as Iestin or the Latin form Justinus) according to others, he was active in the 7th century. He is said to have been the son of Geraint ab Erbin, a ruler of Dumnonia (a Celtic kingdom in what is now southwest England). His brothers were recorded as including Cador, Duke of Cornwall, and Cyngar (another saint who is commemorated in the name of the church at Llangefni, Anglesey). Iestyn, a hermit and confessor who was probably a follower of the Anglesey saint Cybi, founded two churches in north Wales: one, St Iestyn's Church, Llaniestyn, Gwynedd, and another St Iestyn's Church, Llaniestyn in Anglesey. He may also have founded the church at St Just in Roseland, in a part of modern-day Cornwall within his father's influence, and has also been linked with a church in Brittany, in northern France.

His feast day is not included in the Welsh calendars of saints, but was marked at his church on Anglesey on 12 April and 10 October, and at his church in Caernarfonshire on 10 October.