Dionotus

thumb|Dionotus, Saint Ursula's father, in a 1495 painting by [[Vittore Carpaccio]] Dionotus was a legendary king of Cornwall in Geoffrey of Monmouth's Historia regum Britanniae, an account of the rulers of Britain based on ancient Welsh sources and disputed by many historians. Dionotus succeeding his brother Caradocus, and was regent of Britain during the campaigns in Gaul of Emperor Magnus Maximus. The curious thing about this king is that the Welsh chronicles, which parallel most of Geoffrey of Monmouth's book, do not mention this king by name. However, Geoffrey uses Latin versions of Welsh names so he could be referring to Dynod, duke of Cornwall, or Anwn Dynod, Maximus's own son.

Nothing is said of Dionotus until he became king under Maximus. He is first mentioned when Conan Meriadoc, king of Brittany sends a request to Britain for Briton women to help populate his country. Dionotus, being extremely noble and powerful, accepted the request and sent seventy-two thousand women to Gaul. The ships, however, became lost at sea and most of the women died or were captured by barbarians.