The man commemorated by the Tristan Stone near the Castle Dore in Cornwall.
The inscription on the stone, written probably in the sixth century, reads,
Here lies Drustanus, son of Cunomorus.
Cunomorus is identified with Mark in Wrmonoc’s Life of St. Paul Aurelian, and the Tristan legend is usually localized in Cornwall, so Drustanus may be the origin of Tristan (he precedes the Pictish king Drust).
If Cunomorus is Mark, the identification of Tristan as his son is unusual, though in one Welsh Triad, “Drystan” is called the son of “March”.