Ridulph, Rycolf
The chosen ruler of Norway following the death of King Sichelm. Though the dead king had bequeathed the kingdom to Lot, his grandson, the people chose Riculf.
Arthur, however, after pacifying Britain, enforced Lot’s rightful claim to the throne by sailing to Norway, invading the country and killing Riculf.
Sources
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Brut | Layamon, late 12th century to mid-13th century