Owain Glyndŵr - Wikipedia

On September 16, 1400, Owain Glyndŵr was declared Prince of Wales by his followers. From the article:

"Glyndŵr was a descendant of the Princes of Powys through his father Gruffudd Fychan II, hereditary Tywysog of Powys Fadog and Lord of Glyndyfrdwy, and of those of Deheubarth through his mother Elen ferch Tomas ap Llywelyn ab Owen.[1] On 16 September 1400, Glyndŵr instigated the Welsh Revolt against the rule of Henry IV of England. The uprising was initially very successful and rapidly gained control of large areas of Wales, but it suffered from key weaknesses – particularly a lack of artillery, which made capturing defended fortresses difficult, and of ships, which made their coastlands vulnerable. The uprising was eventually suppressed by the superior resources of the English. Glyndŵr was driven from his last strongholds in 1409, but he avoided capture and the last documented sighting of him was in 1412. He twice ignored offers of a pardon from his military nemesis, the new king Henry V of England, and despite the large rewards offered, Glyndŵr was never betrayed to the English. His death was recorded by a former follower in the year 1415.

Glyndŵr is portrayed in William Shakespeare's play Henry IV, Part 1 (anglicised as Owen Glendower) as a wild and exotic man ruled by magic and emotion.

With his death Owain acquired a mythical status along with Cadwaladr, Cynan and Arthur as the hero awaiting the call to return and liberate his people. In the late 19th century the Cymru Fydd movement recreated him as the father of Welsh nationalism."