Pabo Post Prydain was a king somewhere in the Hen Ogledd

Hen Ogledd

Yr Hen Ogledd is a Welsh term used by scholars to refer to those parts of what is now northern England and southern Scotland in the years between 500 and the Viking invasions of c. 800, with particular interest in the Brythonic-speaking peoples who lived there.The term is derived from heroic...

 or Old North of sub-Roman Britain

Sub-Roman Britain

Sub-Roman Britain is a term derived from an archaeological label for the material culture of Britain in Late Antiquity: the term "Sub-Roman" was invented to describe the potsherds in sites of the 5th century and the 6th century, initially with an implication of decay of locally-made wares from a...

.

According to the Old Welsh genealogies of British Library, Harleian MS 3859

Harleian genealogies

The Harleian genealogies are a collection of Old Welsh genealogies preserved in British Library, Harleian MS 3859. Part of the Harleian Collection, the manuscript, which also contains the Annales Cambriae and a version of the Historia Brittonum, has been dated to c. 1100, although a date of c.1200...

, he was a son of Cenau ap Coel Hen. Later Welsh genealogies insert two generations between Pabo and Cenau by making the former a son of Arthwys ap Mar ap Cenau ap Coel, but this presents chronological problems.

The genealogies give a him both a royal line of descendants, namely as the father of Dunod Fawr

Dunod Fawr

Dunod Fawr is a figure known from the Welsh Genealogies believed to have been a noble in the post-Roman Hen Ogledd. Dunod was a son of Pabo Post Prydain and is believed to have succeeded his father as ruler of a small polity somewhere in what is now the North of England, possibly in Lonsdale and/or...

, Sawyl Penuchel

Sawyl Penuchel

Sawyl Penuchel or Ben Uchel , also known as Samuil Penisel , was a British king of the sub-Roman period, who appears in old Welsh genealogies and the Welsh Triads....

 and Ardun Benasgell, and a saintly one, as the grandfather of Deiniol

Deiniol

Saint Deiniol was the first Bishop of Bangor in the Kingdom of Gwynedd, Wales. He is also venerated in Brittany as Saint Denoual. In English, the name is translated as Daniel but this is rarely used....

, Asaph

Saint Asaph

Saint Asaph was, in the second half of the 6th century, the first or second Bishop of St Asaph, i.e. bishop of the diocese of Saint Asaph, the Welsh See now of that name.-Biography:...

 and Tysilio

Tysilio

Saint Tysilio was a Welsh bishop, prince and scholar, son of the reigning King of Powys, Brochwel Ysgithrog, maternal nephew of the great Abbot Dunod of Bangor Iscoed and an ecclesiastic who took a prominent part in the affairs of Wales during the distressful period at the opening of the 7th...

.

In genealogical and literary sources, he is known by his epithet 'Post Prydain' meaning "the Pillar of Britain".

Llanbabo

A later tradition, which is unattested before the 14th century, identifies Pabo with the eponymous founder of St Pabo's Church, Llanbabo

St Pabo's Church, Llanbabo

St Pabo's Church, Llanbabo is a medieval church in Llanbabo, in Anglesey, North Wales. Much of the church dates to the 12th century, and it is regarded as a good example of a church of its period that has retained many aspects of its original fabric...

 (at Llanbabo

Llanbabo

Llanbabo is a small village two miles north west of Llannerch-y-medd in Anglesey, Wales.The ancient church of St Pabo, Llanbabo is dedicated to Saint Pabo: possibly Pabo Post Prydain, one of the leaders among the Britons of the Hen Ogledd following the withdrawal of the Roman legions...

, Anglesey

Anglesey

Anglesey , also known by its Welsh name Ynys Môn , is an island and, as Isle of Anglesey, a county off the north west coast of Wales...

). The first author to record it is antiquarian Henry Rowlands

Henry Rowlands

Henry Rowlands was the author of Mona Antiqua Restaurata: An Archaeological Discourse on the Antiquities, Natural and Historical, of the Isle of Anglesey, the Antient Seat of the British Druids The Bridestones were among the sites described by Rowlands....

 (d. 1723), who writes that "Pabo, frequently called Post Prydain, i.e. the Support of Britain, for his great valour against the Picts and Scots, retired here [in Anglesey], and built his church at Llan Babo." The identification appears to go back to at least the 14th century, when a stone cross was erected in the ruler's memory in the abbey's churchyard. Welsh poet Lewis Morris reports that the memorial cross was discovered there around 1650. The monument bears the carved image of a king and an accompanying inscription. The inscription is in part illegible, but the following reading has been suggested:

Hic iacet Pa[bo] Post Priid Co[nf Gr] … [t]el [i]ma[ginem obtulit]

"Here lies Pabo the Upholder of Britain, Confessor, Gruffudd ab Ithel offered (this) image"

In the absence of any early evidence that the northern ruler ever travelled south or abdicated to devote himself to the church, the tradition is probably spurious. The identity of the historical Pabo who did give his name to the church remains unknown.