Bran the Blessed, the son of Llyr Llediaith, who first brought the faith of Christ to the nation of the Cymry from Rome, where he was seven years a hostage for his son Caradawc, whom the Romans made prisoner through the craft, and deceit, and treachery of Aregwedd Foeddawg (usually supposed to be Cartismandua).
The second was Lleurig ab Coel ab Cyllyn Sant, who was called Lleufer Mawr, (the great Light), and built the ancient church at Llandaff, which was the first in Britain, and who gave the privileges of land, and of kindred, and of social rights, and of society to such as were of the faith of Christ.
The third was Cadwaladyr the Blessed, who gave refuge, with his lands, and with all his goods, to the believers who fled from the Saxons without faith, and from the aliens who would have slain them.
Sources
Red Book of Hergest | C. 1425
Text of the Mabinogion and Other Welsh Tales | John Rhys, 1887