Llywarch Hen (meaning ‘Llywarch the Old’) was a 6th century prince of the Brythonic House of Rheged, a ruling family in the Hen Ogledd or ‘Old North’ of Britain (modern southern Scotland and northern England). He was first cousin to King Urien Rheged and may possibly have been a monarch himself in the same region.
His life was the subject of a presumed lost saga of which only the poetry, a series of englynion, survives. The words are put into the mouth of Llywarch himself, although they were clearly composed somewhat later, possibly in the 9th century. He bemoans the death of Urien and returns to Rheged with his severed head. Other Brythons make war on Llywarch and he is soon found living in poverty. He is advised to flee to Powys and this he does. He is also sometimes associated with Llanfor, near Llyn Tegid in Gwynedd.
In the poems about Llywarch, known as Canu Llywarch Hen, it is said he had twenty-four sons, but various sources list as many as thirty-nine, plus a few daughters. The Canu Heledd, concerning the fall of the kings of the Pengwern region, and the Elegy for Geraint, concerning the Battle of Llongborth, are also associated indirectly with Llywarch.