Owain ap Gruffudd (, ) or Owain Gwynedd () was King of Gwynedd from 1137 until his death in 1170, succeeding his father Gruffudd ap Cynan. He is known as Owain Gwynedd to distinguish him from the contemporary Powysian ruler, Owain Cyfeiliog, whose name was also Owain ap Gruffudd. and annexed Ceredigion to their father's realm.
Accession to the throne and early campaigns
On behalf of his father, Gruffudd ap Cynan, Gwynedd directed military operations to the "cantrefs of Meirionnydd, Rhos, Rhufoniog and Dyffryn Clwyd to Gwynedd proper", and it was against the Normans, with Gruffudd ap Rhys he secured a victory at the Battle of Crug Mawr and the temporary occupation of Kingdom of Ceredigion. In 1146 he captured Mold Castle and about 1150 captured Rhuddlan and encroached on the borders of Powys. The prince of Powys, Madog ap Maredudd, with assistance from Ranulf de Gernon, 4th Earl of Chester, gave battle at Coleshill, but Owain was victorious. The fleet accompanying the invasion made a landing on Anglesey where it was defeated. Ultimately, at the end of the campaign, Owain was forced to come to terms with Henry, being obliged to surrender Rhuddlan and other conquests in the east.
Madog ap Maredudd died in 1160, enabling Owain to regain territory in the east. In 1163 he formed an alliance with Rhys ap Gruffudd of Deheubarth to challenge English rule. King Henry again invaded Gwynedd in 1165, In the last of his letters to Louis VII of France, he offered to become a vassal of the French king and assist in attacking Henry if the French would make war on him. This time Owain styled himself (Prince of Wales), the first time he or anyone is known to have used such a title.
At the time, the word prince, deriving as it did from the Latin princeps, meant "first person, chief leader; ruler, sovereign." It wasn't until the 14th century that it came to mean "heir to the throne". Thus, Owain, by designating himself princeps, was calling himself the principal ruler of Wales.
Henry did not invade Gwynedd again, and Owain was able to regain his eastern conquests, recapturing Rhuddlan Castle in 1167 after a siege of three months. an account of his father's life. Following his death, civil war broke out between his sons. Owain was married twice, first to Gwladus ferch Llywarch ap Trahaearn, by whom he had two sons, Maelgwn ab Owain Gwynedd and Iorwerth Drwyndwn, the father of Llywelyn ab Iorwerth (Llywelyn the Great), then to Cristin, by whom he had three sons including Dafydd ab Owain Gwynedd and Rhodri ab Owain Gwynedd. He also had a number of illegitimate sons, who by Welsh law had an equal claim on the inheritance if acknowledged by their father.
Heirs and successors
thumb|150px|right|There is no evidence Owain used a coat of arms during his life, but later antiquarians [[Attributed arms|retroactively attributed to Owain Gwynedd the blazon: Vert, three eagles displayed in fess Or.]]
Gwynedd was married, firstly to Gwladus daughter of Llywarch ap Trahaearn and then to his first cousin Cristin ferch Goronwy. Owain had originally designated Rhun ab Owain Gwynedd as his successor. Rhun was Owain's favourite son,
- Margaret ferch Owain Gwynedd;
- Iefan ab Owain Gwynedd;
- Cynan ab Owain Gwynedd, Lord of Meirionnydd (illegitimate);
- Rhirid ab Owain Gwynedd (illegitimate);
- Madoc ab Owain Gwynedd (illegitimate) (speculative/legendary);
- Cynwrig ab Owain Gwynedd (illegitimate);
- Gwenllian II ferch Owain Gwynedd (also shared the same name with a sister);
- Einion ab Owain Gwynedd (illegitimate);
- Iago ab Owain Gwynedd (illegitimate);
- Ffilip ab Owain Gwynedd (illegitimate);
- Cadell ab Owain Gwynedd (illegitimate);
- Rotpert ab Owain Gwynedd (illegitimate);
- Idwal ab Owain Gwynedd (illegitimate);
- Other daughters.
Fiction
Owain is a recurring character in the Brother Cadfael series of novels by Ellis Peters, often referred to, and appearing in the novels Dead Man's Ransom and The Summer of the Danes. He acts shrewdly to keep Wales' borders secure, and sometimes to expand them, during the civil war between King Stephen and Matilda, and sometimes acts as an ally to Cadfael and his friend, Sheriff Hugh Beringar. Cadwaladr also appears in both these novels as a source of grief for his brother. Owain appears as a minor character in novels of Sharon Kay Penman concerning Henry II and Eleanor of Aquitaine (When Christ and His Saints Slept and Time and Chance). Her focus with respect to Owain is on the fluctuating and factious relationship between England and Wales.