Son of Hengist and brother of Ebissa in Geoffrey of Monmouth’s Historia and the other chronicles.
Octa’s father, a great Saxon leader, brought Octa to Britain during the reign of King Vortigern, Hengist’s brother-in-law. When Hengist’s plan to conquer Britain became known, Vortigern and his successors went to war with the Saxons. Octa succeeded his father as the Saxon leader after Hengist was executed by King Ambrosius.
Ambrosius defeated Octa, forced baptism on him, and banished him to Scotland. When Ambrosius died, however, Octa resumed his war against King Uther. He was captured with his kinsman Eosa at Mount Damon by Uther, and was thrown into prison. In time, Octa and Eosa convinced the prison guards to free them, and the lot fled to Germany, where they raised an army and returned. Geoffrey says that Octa was finally killed at Saint Albans (or Verulam) by Uther’s army.
In Nennius (whose chronicle predates Geoffrey), it is uncertain whether Octa is the Saxon commander in the battles against Arthur, but the possibility is open. Geoffrey attributes this campaign to Octa’s successor, Colgrim.
Richard Blackmore gives Octa a daughter named Ethelina, who married Arthur. Octa may be related to the Welsh character Osla Big-Knife.
Arthur’s Battles | The Legend of King Arthur
Historia Brittonum | Probably Nennius, early 9th century
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Prince Arthur: An Heroick Poem: In Ten Books | Sir Richard Blackmore, 1695