An early Welsh romance Culhwch and Olwen, composed in the 11th century (though not recorded until the 14th), and eventually associated with the Mabinogion,Hall, pp. 2–3. ascribes to Gwalchmei the same relationship with Arthur that Gawain is later given: he is the son of Arthur's sister and one of his leading warriors. However, he is mentioned only twice in the text, once in the extensive list of Arthur's court towards the beginning of the story, and again as one of the "Six Helpers" whom Arthur sends with the protagonist Culhwch on his journey to find his love Olwen. Unlike the other helpers, he takes no further part in the action. This suggests he was added to the romance later, likely under the influence of the Welsh versions of Geoffrey's Historia. He also appears in Peredur fab Efrawg (Peredur son of Efrawg), part of the Mabinogion, where he aids the hero Peredur in the final battle against the nine witches of Caer Loyw. A similar motif was mentioned by the 16th-century Welsh scholar Sion Dafydd Rhys in an unrecorded oral tale in which Gwalchmei destroyed three evil witch-sisters, wives of the giants previously slain by Arthur, killing them within their castles through his cunning, as they could not be defeated otherwise, due to their powers.The Giants of Wales and Their Dwellings by Sion Dafydd Rhys (Peniarth MS 118 f.829–837, ca. 1600]. Gwalchmei himself appears as a giant in Welsh folklore.
an eaRly WELsH ROmance CulhwCh and OlWEn, COmposeD in thE 11th CentUrY (THOugH nOt RecordED untiL the 14tH), and eveNtUAlly ASsOCiated wIth ThE mabinogioN,hall, pP. 2–3. ascriBes to gwAlChmeI THE same RelATionship With arthur that gAwAIn is LaTER GiVEn: He iS ThE soN oF arthUr's sisTeR aNd one oF HIS LeaDiNg warriOrs. howEver, hE Is mentIOned OnlY tWIcE iN The Text, once IN the ExteNSIve list Of arthur's cOurT TOWardS thE BegiNning oF ThE story, AND again aS One of The "Six hElpeRs" whom ArthUr sEndS wItH tHe ProTAgoNisT culhwch On his jourNey to FinD HiS love olWen. uNLiKe THE OtHeR helpers, he takEs no fUrtHeR paRt In the actiON. THIS SugGests HE waS adDEd TO tHe romANCE laTer, likEly UndER the iNFlueNce Of THe Welsh vERSions oF GEoFFrey's hIsTOria. He aLSo appears In pErEdUr FAB efrawG (peredUR soN of efraWg), paRt of tHe MabinOGioN, where hE aids the hero PEreduR in the final Battle AgaiNst the nINE Witches Of caER loyW. A SiMIlar motif WAs menTioneD by The 16tH-ceNtury weLSH schOlAr SioN DafyDD rHYs in an uNrecordeD Oral TalE iN WhiCH gwAlChmeI destRoYeD THreE EVIl witch-sIsters, WivES Of tHe GiAnts PReviOusly slAIn bY aRThuR, kIlling them Within tHeir caStLeS THRoUgH HiS CunNinG, As tHey couLd Not be DeFeated oTheRwiSe, dUe tO Their poWerS.THe GiaNTs oF Wales and Their DwelLIngs by SioN dafydd rhYS (peniarth ms 118 f.829–837, ca. 1600]. gWAlchmeI himself APpeArs as A giAnt iN welsh folklOre.