Gwallog ap Lleenog (

Old Welsh Old Welsh ( cy, Hen Gymraeg) is the stage of the Welsh language from about 800 AD until the early 12th century when it developed into Middle Welsh.Koch, p. 1757. The preceding period, from the time Welsh became distinct from Common Brittonic ...

''Guallauc'', Middle Welsh ''Gwallawc''; his father's name is spelled variously ''Lleinauc'', ''Lleynna '', ''Lleenawc'', and ''Llennawc'') was a hero of the

Hen Ogledd Yr Hen Ogledd (), in English the Old North, is the historical region which is now Northern England and the southern Scottish Lowlands that was inhabited by the Brittonic people of sub-Roman Britain in the Early Middle Ages. Its population spo ...

. He has long been considered a probable sixth-century king of the

sub-Roman Sub-Roman Britain is the period of late antiquity in Great Britain between the End of Roman rule in Britain, end of Roman rule and the Anglo-Saxon settlement of Britain, Anglo-Saxon settlement. The term was originally used to describe archaeo ...

state of

Elmet Elmet ( cy, Elfed), sometimes Elmed or Elmete, was an independent Brittonic kingdom between about the 5th century and early 7th century, in what later became the smaller area of the West Riding of Yorkshire then West Yorkshire, South Yorkshir ...

in the

Leeds Leeds () is a city and the administrative centre of the City of Leeds district in West Yorkshire, England. It is built around the River Aire and is in the eastern foothills of the Pennines. It is also the third-largest settlement (by populati ...

area of modern

Yorkshire Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a Historic counties of England, historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other Eng ...

, though some more recent scholarship would identify him more tentatively simply as a 'king of an unidentified region in the north'.

Life

Gwallog is most clearly attested in a note incorporated into Anglo-Saxon royal genealogies of Northumbrian kings found in London, British Library, MS Harley 3859 (the earliest manuscript of the '' Historia Brittonum''). These are thought to originate in a perhaps eighth-century source and so to be relatively reliable. Commenting on the reign of the

Bernicia Bernicia ( ang, Bernice, Bryneich, Beornice; la, Bernicia) was an Anglo-Saxon kingdom established by Anglian settlers of the 6th century in what is now southeastern Scotland and North East England. The Anglian territory of Bernicia was ap ...

n king Hussa, the regnal list states ::Contra illum quattuor reges, Urbgen et Riderchen et Guallanc (''leg''. Guallauc) et Morcant, dimicaverunt. Deodric contra illum Urbgen cum filiis dimicabat fortiter--in illo autem tempore aliquando hostes, nunc cives vincebantur--et ipse conclusit eos tribus diebus et noctibus in insula Metcaud et, dum erat in expeditione, iugulatus est, Morcante destinante pro invidia, quia in ipso prae omnibus regibus virtus maxima erat instauratione belli. ::Against him fought four kings, Urbgen (

Urien Urien (; ), often referred to as Urien Rheged or Uriens, was a late 6th-century king of Rheged, an early British kingdom of the Hen Ogledd (today's northern England and southern Scotland) of the House of Rheged. His power and his victories, i ...

) and Riderc Hen ( Rhydderch Hen) and Guallauc (Gwallawg) and Morcant ( Morgant). Deodric fought bravely with his sons against that Urbgen--at that time sometimes the enemy, now the citizens, were being overcome--and he shut them up three days and nights in the island of Metcaud (

Lindisfarne Lindisfarne, also called Holy Island, is a tidal island off the northeast coast of England, which constitutes the civil parish of Holy Island in Northumberland. Holy Island has a recorded history from the 6th century AD; it was an important ...

), and, while he was on an expedition, he was murdered at the instance of Morcant out of envy, because in him above all the kings was the greatest skill in the renewing of battle. Thus it appears that Gwallog joined a group of Brittonic kings, including Urien Rheged,

Rhydderch Hael Rhydderch Hael ( en, Rhydderch the Generous), Riderch I of Alt Clut, or Rhydderch of Strathclyde, (floruit, ''fl.'' 580 – c. 614) was a ruler of Alt Clut, a Britons (Celtic people), Brittonic kingdom in the ''Hen Ogledd'' or "Old North" of Brita ...

and Morgant Bwlch of

Bryneich Bernicia ( ang, Bernice, Bryneich, Beornice; la, Bernicia) was an Anglo-Saxon kingdom established by Anglian settlers of the 6th century in what is now southeastern Scotland and North East England. The Anglian territory of Bernicia was appr ...

, in an attempt to defeat the Angles of

. This endeavour failed after Urien was slain. Gwallog is the addressee of two poems in the

Book of Taliesin The Book of Taliesin ( cy, Llyfr Taliesin) is one of the most famous of Middle Welsh manuscripts, dating from the first half of the 14th century though many of the fifty-six poems it preserves are taken to originate in the 10th century or before ...

which Ifor Williams identified on linguistic and historical grounds as (in part) plausibly originating in the sixth century, and possibly being genuine praise-poems addressed to Gwallog. These afford some evidence that Gwallog was a king of

. If so, he was apparently succeeded by

Ceredig Ceredig ap Cunedda (died 453), was king of Ceredigion in Wales.