The Vita Sancti Gundleii (in English the Life of Saint Gwynlliw) is a medieval saint’s life, composed in Cemis, Pembrokeshire, in the 12th century. A copy survies in the British Museum Cotton MS Vespasian A xiv. Gwynlliw married Gwladys the daughter of King Brychan Brycheiniog. According to the Vita sancti Gundleii, Gwynlliw was given Gwladys peacibly by her father, making no mention of the account in the Vita Sancti Cadoci according to which Gwynlliw abducted Gwladys from her father and was aided in the following battle by Arthur, Kay, and Bedwyr.