"king arthur and king cornwall" is an english ballad surviving in fragmentary form in the 17th-century percy folio manuscript. an arthurian story, it was collected by francis james child as child ballad 30. unlike other child ballads, but like the arthurian "the boy and the mantle" and "the marriage of sir gawain", it is not a folk ballad but a professional minstrel's song. it is notable for containing the green knight, a character known from the medieval poems "the greene knight" and the more famous "sir gawain and the green knight"; he appears as "bredbeddle", the character's name in "the greene knight".