A Son of Gorbonianus was a legendary king of the Britons as accounted by Geoffrey of Monmouth

Geoffrey of Monmouth

Geoffrey of Monmouth was a cleric and one of the major figures in the development of British historiography and the popularity of tales of King Arthur...

. He was a son of King Gorbonianus

Gorbonianus

Gorbonianus was a legendary king of the Britons as accounted by Geoffrey of Monmouth. He was the eldest son of King Morvidus, and the brother of Archgallo, Elidurus, Ingenius, and Peredurus, and...

 but was never given a name in the text.

According to Geoffrey, he was a good and prudent king who emulated his uncle and predecessor, Elidurus

Elidurus

Elidurus the Dutiful was a legendary king of the Britons as accounted by Geoffrey of Monmouth. He was the third son of King Morvidus and brother of Gorbonianus, Archgallo, Ingenius, and Peredurus....

. He was just and compassionate to his people and never faltered in his righteousness to them. When he died, he was succeeded by his cousin, Marganus

Marganus II

Marganus II was a legendary king of the Britons as accounted by Geoffrey of Monmouth. He was the son of King Archgallo and was succeeded by his brother Enniaunus. He ruled the kingdom in tranquility and without conflict....

, the son of Archgallo

Archgallo

Archgallo was a legendary king of the Britons as accounted by Geoffrey of Monmouth. He was the second son of King Morvidus and brother of Gorbonianus....

.