https://en.wikipedia.org/wiki/Vortimer

Vortimer , also known as Saint Vortimer , is a figure in British tradition, a son of the 5th-century Britonnic ruler Vortigern. He is remembered for his fierce opposition to his father's Saxon allies. In Geoffrey of Monmouth's Historia Regum Britanniae, he overthrows his father and reigns as King of Britain for a brief period before his death restores Vortigern to power.

https://en.wikipedia.org/wiki/Vortigern

Vortigern , also spelled Vortiger and Vortigen, was a 5th-century warlord in Britain, a leading ruler among the Britons. His existence is considered likely, but information about him is shrouded in legend.

He may have been the "superbus tyrannus" said to have invited Hengist and Horsa to aid him in fighting the Picts and the Scots. However, they revolted, killing his son in the process and adding Sussex and Essex to their own kingdom. It is said that he took refuge in North Wales, and that his grave was in Dyfed or the Llŷn Peninsula. He is cited at the head of the genealogy of the early Kings of Powys.

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