Born in Armorica, he appears to have been married and to have had a military background - his Life makes his father, a minor Breton prince named Bican Farchog, Arthur's uncle on his mother's side.
The Brecon Beacons Mountain Centre stands next to Mynydd Illtud on its eastern side and provides advice for visitors wishing to enjoy the area.
There are references to Illtud being the cousin of Athrwys ap Meurig of Morgannwg although there is no known connection with Sadwrn.