Y Mab Darogan (pronounced [ə mɑːb darɔˈɡan] meaning "The Destined/Prophesised Son" or "Son of Destiny") is a messianic figure of Welsh legend, destined to force the English out of Britain and reclaim it for its Celtic inhabitants. A number of figures have been called Y Mab Darogan in history (other titles include Y Gŵr Darogan and Y Daroganwr). An extensive corpus of medieval Welsh prophetic verse, beginning with Armes Prydain (10th century?), is centred on the figure of Y Mab Darogan.
Some later poetry associated Y Mab Darogan with the legendary King Arthur. Arthur was often seen as protector figure who defended the Britons against all manner of threats. He is specifically indicated as fighting the Saxons in the 9th-century text Historia Brittonum and in works based on it. However, Arthur does not appear in the Armes Prydain and other early prophetic works.
An awdl by Dafydd Benfras hails 'Llywelyn' as y daroganwr ("son of the prophecy"; Y Mab Darogan). The poem is difficult to date and may be addressed to either Llywelyn ab Iorwerth (Llywelyn the Great) or his grandson Llywelyn ap Gruffudd (Llywelyn the Last); it is accepted with some hesitation as being an ode to Llywelyn ab Iorwerth by the most recent editor in the series Beirdd y Tywysogion, but it is noted that it might well be addressed to Llywelyn ap Gruffudd (Dafydd Benfras is associated with both). At the end of the ode, which praises Llywelyn as 'king of the Welsh' (brenin y Cymry), the poet declaims "Whatever is prophesised about you you shall take, / From every prophetic song you shall be blessed, / That which I have prophesised you shall possess, / Whatever I should prophesise you shall uphold, / You are the son of the prophecy in the eyes of all whom you see (about you)!'.