Sir Calogrenant, sometimes known in English as Colgrevance, or, in ancient Welsh, Cynon ap Clydno, is a Knight of the Round Table in Arthurian legend. He is a cousin to Sir Ywain, and his courtesy and eloquence were known throughout the kingdom. Calogrenant appears in the Welsh Romance Owain, or the Lady of the Fountain as Cynon, known elsewhere in Welsh tradition as the lover of Owain's sister Morvydd. Cynon is stated to be the son of Clydno, possibly connected to Clyddno Eiddin.