Peredur son of Efrawg is one of the Three Welsh Romances associated with the Mabinogion. It tells a story roughly analogous to Chrétien de Troyes' unfinished romance Perceval, the Story of the Grail, but it contains many striking differences from that work, most notably the absence of the French poem's central object, the grail.

The Three Welsh Romances are three Middle Welsh tales associated with the Mabinogion. They are versions of Arthurian tales that also appear in the work of Chrétien de Troyes. Critics have debated whether the Welsh Romances are based on Chrétien's poems or if they derive from a shared original. The Romances survive in the White Book of Rhydderch and the Red Book of Hergest, both from the 14th century, though the material is at least as old as Chrétien.