
1) English boy name 2) Legendary British king 3) Male Shakespearean character
Found on
https://www.crosswordclues.com/clue/guiderius

Guiderius (Welsh Gwydr) is a legendary British king according Geoffrey of Monmouth`s Historia Regum Britanniae (History of the Kings of Britain) and related texts. He can probably be identified as deriving from the historical Togodumnus. The eldest son of Cymbeline, he succeeds his father to the kingship of Britain. Cymbeline had voluntarily paid....
Found on
http://en.wikipedia.org/wiki/Guiderius

Guiderius is a son to Cymberline disguised under the name Polydore.
Found on
http://www.probertencyclopaedia.com/K2.HTM
No exact match found.