Vthyr (Bendragon; Uthyr Penndra(g)on: "Chief Dragon" - dragon being a euphemism for warrior in the oldest Welsh poetry*. Uthr means "terrible"*). While there is no definitive evidence of Uythr being Arthur's father before Geoffrey of Monmouth* (See Other Works), Uythr appears in the Arthurian poems Pa mor (English translation), which is likely to be 10th or 11th C.*, and Marvnat vthyr pen. ("The Death-song of Uthyr Pen.": English translation). The poem Ymddiddan Arthur a'r Eryr ("The Colloquy of Arthur and the Eagle": English translation) suggests Vrthyr's son, Madawc, had a child that was Arthur's nephew. While this poem isn't pre-Geoffrey in its current form*, it does suggest an independent tradition as Madawc isn't mentioned by Geoffrey*.

Uthyr appears in the Welsh Triads* (See Other Works) twice. He appears as one of the people knowing one of the "Three Great Enchantments of the Island of Britain". What this enchantment is is not clear. Geoffrey gives us the tale of Uthyr, with help from Merlin, taking on the form of Gorlois (Gwrleis), duke of Cornwall, to sleep with his wife Igerna (Eigr) and thus beget Arthur*. The Triad notes that Uthyr passed on his enchantment secret to Menw son of Teirgwaedd, and in the Welsh tale Culhwch ac Olwen (Summary) this person is given as a shapeshifter, perhaps suggesting Uthyr originally needed no help in the seduction* and had the trick already up his sleeve.

The second Triad he appears in is the heavily influenced by Geoffrey "The Three Men of Shame who were in the Island of Britain"*. In this he is listed as brother of Emrys Wledig and killer, with him, of the treacherous Gwrtheyrn the Thin [Vortigern] who invited the Saxons into Britain and exiled the brothers to Armorica*. Though this is hardly a source worth relying on, it would place him c.449 CE according to the Anglo-Saxon Chronicles (See Other Works).