Anwn Dynod / Antonius Donatus Gregorius (c.382 - c.400?)

When Magnus Maximus left Britain to pursue his imperial ambitions on the continent, he left behind his British wife, Elen Lwyddog, and their children. Having become Western Roman Emperor in 383 AD, and perhaps foreseeing the fading of Roman administration in the provinces, Magnus Maximus returned to Britain and began transferring local authority to local leaders. This extended to his sons - Owain Finddu, Anwn Dynod and Custennin - who were given control of territories in Wales. 

Anwn Dynod's protectorate was based in southwestern
Wales, centred on the territories of the Demetae tribe.
Over time, the territory became the kingdom of Dyfed.

Like his brothers, Anwn Dynod - otherwise known as Antonius Donatus Gregorius -  appears to have been accepted by the Britons as a leader. His protectorate of Southwest Wales was centred on the territories of the Celtic Demetae tribe and his capital was most likely at Moridunum (modern-day Caermarthen). Anwn Dynod would have ruled more as a Roman governor rather than a Celtic king and, although he and his brothers have been given Welsh names by later chroniclers, it's much more likely they would have considered themselves Roman.

As Roman control over the remote areas of Britain crumbled in the late fourth century, Irish warbands started to raid along the Welsh coast, seizing booty in the form of cattle, corn and captives to sell into slavery. Much of Anwn's reign was spent fighting off these raiders with the help of Aed Brosc and his Desai warriors who had been settled in southwestern Wales several years earlier by Magnus Maximus. 

Anwn Dynod's death is not recorded but he probably didn't live to see the Roman withdrawal in 410 AD. It is entirely possible that, like his brother, Owain, he was killed in battle with the Irish. He was succeeded by his son, Ednyfed - or Demetius to give him his Roman name - who later founded the kingdom of Dyfed.