Thus Arthur, "the once and future king", is an illegitimate child (though later legend, as found in Malory, emphasises that the conception occurred after Gorlois's death and that he was legitimated by Uther's subsequent marriage to Igraine[3]).

[6] According to Robert de Boron[7] and the cycles based on his work, it was Uther's older brother (elsewhere called Aurelius Ambrosius and likely based on Ambrosius Aurelianus) who saw the comet and received the name "Pendragon", Uther taking his epithet after his death.

An alternative possibility is it stems from adopting the use of the draco military standard of the Roman cavalry, but this is likely a historical conjecture.

[6] In Triad 28, Uthyr is named the creator of one of the Three Great Enchantments of the Island of Britain, which he taught to the wizard Menw.

It follows Geoffrey's description of Uther as brother of both Aurelius Ambrosius ("Emrys Wledig") and Constans II ("Custennin the Younger").

With Aurelius on the throne, Uther leads his brother in arms to Ireland to help Merlin bring the stones of Stonehenge from there to Britain.

On the way to the battle, he sees a comet in the shape of a dragon, which Merlin interprets as presaging Aurelius's death and Uther's glorious future.

Uther wins the battle and takes the epithet "Pendragon", and returns to find that Aurelius has been poisoned by an assassin.

He secures Britain's frontiers and quells Saxon uprisings with the aids of his retainers, one of whom is Gorlois, Duke of Cornwall.

Uther consults with Merlin who uses his magic to transform the king into the likeness of Gorlois and thus gain access to Igerna at Tintagel.

He defeats Hengist's son Octa at Verulamium (St Albans), despite the Saxons calling him the "Half-Dead King".

It is possible that Uther himself is based at least partially on Tewdrig, a historical king of Glywysing in the sixth century, given the strong similarities between their death stories.

Early German literature's motif of Uther's descent from fairies, believed to have relied on some now lost Celtic material, may have been meant to explain Arthur's connection with Avalon.