Ragnald IV of the Isle of Man

Rǫgnvaldr Guðrøðarson
King of the Isles
Rǫgnvaldr's name and title as it appears on folio 154r of Oxford Jesus College MS 111 (the Red Book of Hergest): "Reinaỻt urenhin yr ynyssed".
Reign	1187–1226
Predecessor	Guðrøðr Óláfsson
Successor	Óláfr Guðrøðarson
Died	14 February 1229 Tynwald
Burial	St Mary's Abbey, Furness
Issue	Guðrøðr Dond
House	Crovan dynasty
Father	Guðrøðr Óláfsson

Rǫgnvaldr Guðrøðarson (died 14 February 1229) ruled as King of the Isles from 1187 to 1226. He was the eldest son of Guðrøðr Óláfsson, King of Dublin and the Isles. Although the latter may have intended for his younger son, Óláfr, to succeed to the kingship, the Islesmen chose Rǫgnvaldr, who was likely Óláfr's half-brother. Rǫgnvaldr went on to rule the Kingdom of the Isles for almost forty years before losing control to Óláfr.

Acclaimed in one near contemporary Scandinavian source as "the greatest warrior in the western lands", Rǫgnvaldr lent military aid to William I, King of Scotland against the disaffected Haraldr Maddaðarson, Earl of Orkney and Caithness, and occupied Caithness for a short period of time at about the turn of the thirteenth century. Like his predecessors, Rǫgnvaldr was closely associated with the rulers of northern Wales. A daughter of his was betrothed to Rhodri ab Owain, a dynast of the ruling family of Gwynedd. In 1193, Rǫgnvaldr lent military aid to Rhodri against his rivals. Rǫgnvaldr was also involved in Irish affairs, as he was the brother-in-law of John de Courcy, one of the most powerful of the incoming Englishmen. With Courcy's eventual fall from power in the first decade of the thirteenth century, Rǫgnvaldr aided him in an unsuccessful attack on Courcy's rivals.

On numerous occasions from 1205 to 1219, Rǫgnvaldr bound himself to the English Crown by rendering homage to John, King of England and his successor, Henry III, King of England. In return for his vassalage, these English rulers promised to assist Rǫgnvaldr against any threats to his realm, whilst Rǫgnvaldr pledged to protect English interests in the Irish Sea zone. With the strengthening of Norwegian kingship in the first half of the century, the Norwegian Crown began to look towards the Isles, and in 1210 the region fell prey to a destructive military expedition. In consequence, Rǫgnvaldr rendered homage to Ingi Bárðarson, King of Norway. The resurgence of Norwegian authority threat may well have been the reason why Rǫgnvaldr submitted to Pope Honorius III in 1219, and promised to pay a perpetual tribute for the protection of his realm.