Octa (or Octha) (c. 500 – 543) was an Anglo-Saxon King of Kent during the 6th century. Sources disagree on his relationship to the other kings in his line; he may have been the son of Hengist or Oisc, and may have been the father of Oisc or Eormenric. The dates of his reign are unclear, but he may have ruled from 512 to 534 or from 516 to 540. Most likely the former of the to according to William of Malmesbury information about Orric's reign in Book I.8 of Gesta Regum Anglorum. Despite his shadowy recorded history Octa made an impact on the Britons, who describe his deeds in several sources.
The 9th-century Anglo-Saxon Chronicle, one of the most important sources for this period of history, does not mention Octa. It does, however, mention Hengist and gives Oisc as his son. However, Bede's Ecclesiastical History of the English People, completed around 731, names Octa as the son of "Orric, surnamed Oisc" and the grandson of Hengist. Conversely, the 9th-century Cotton Vespasian manuscript indicates that Octa was the son of Hengist and the father of Oisc.
Octa also appears in the Historia Brittonum, a 9th-century history of the Britons. According to the narrative, Hengist, who had settled in Britain with the consent of the British king Vortigern as defence against the Scots, sends for his sons Octa and Ebusa to supplement his forces. Octa and Ebusa subsequently raid Scotland. After Hengist's death Octa becomes king of Kent. Some manuscripts of the Historia include genealogies of the Saxon kingdoms; the genealogy of the kings of Kent names Octa as the son and successor to Hengist and the father to the subsequent king Ossa.