Magnus Maximus, Maximianus
The name by which the Roman Emperor Maximus was known in Welsh tradition.
In British folklore he became known as Macsen Wledig. He married Elen (or Helen), daughter of Eudaf (or Odes, or Octavius). He is said to have been later restored as emperor with the help of Elen's brothers Cynan and Gadeon.
He had a daughter, Servia (or Severa), who were married to Vortigern, who became the high king of Britain.
Magnus Maximus was the emperor of Western Rome (Britain, Spain and Gaul) between 25 August 383 and 28 July 388. He was a Spanish solder who accompanied the Spanish general Theodosius the Elder, the commander of an army the emperor Valentinian sent into Britain. After having getting the control over the unsettling Britain, Magnus Maximus were declared emperor by the Roman army in Britain. In time he was accepted as emperor in the West and Theodosius the Younger, who was emperor in the East, acknowledged this.