Heir of Isildur
Heir of Isildur was the title of thirty-nine lords of the Dúnedain descended in right line from Isildur the son of Elendil, from his son Valandil to Aragorn Elessar, who reunited the Kingdoms of the Dúnedain in Middle-earth.
Isildur was the eldest son of Elendil, and so by right he and his heirs should have inherited the title of High King and ruled the Two Kingdoms of Arnor and Gondor. Soon after the defeat of Sauron at the end of the Second Age, Isildur and his three elder sons all perished in the Disaster of the Gladden Fields.
Isildur's only remaining Heir was Valandil, kept safe in Rivendell but only eleven years old at that time, and unable to take up his rule. So, Isildur's nephew Meneldil took control of the kingdom of Gondor, and the Two Kingdoms split from one another as Gondor's rule went to the House of Anárion. In the south, Gondor remained strong under the rule of Meneldil's descendants, but the North-kingdom was not so fortunate. The sons of Eärendur quarreled, and while Amlaith was the Heir of Isildur and his father, the other sons broke the kingdom into three separate realms. Of these, Amlaith ruled Arthedain, the only that was ruled by the Heir of Isildur. The other kingdoms were slowly overcome by dark forces of the evil land of Angmar. By the time Argeleb I of Arthedain came to power, the line of kings had failed in those kingdoms, so Argeleb claimed sovereignty over all of Arnor (taking the royal prefix ar(a)- as a token of this).
Arvedui, Isildur's Heir through twenty-three generations, was the last King to rule in the north; he was also notable for marrying Fíriel, daughter of the King of Gondor Ondoher, thus uniting the House of Isildur and House of Anárion. He later attempted to reclaim the High Kingship, but failed, and the last remnant of royal Arnor was overrun by its enemies.
Though their royal cities were wasted, and their people dwindled, the line of Isildur's Heirs continued for another sixteen generations under the title 'Chieftain of the Dúnedain', who were Arvedui's descendants and ruled the remnants of the Dúnedain of Arnor. When the line of the Kings of Gondor also failed and the Ruling Stewards ruled the Kingdom, it was the Chieftains who held the line of Anárion alive, but they were hidden in the north, forgotten by all except in Imladris where heirs of Isildur were harboured as well as their heirlooms were kept.
The Heir of Isildur was a target of Sauron, if any remained in Middle-earth; when Arathorn II died, the Wise decided to protect his son Aragorn by raising him without telling him of his name and heritage.
- J.R.R. Tolkien, The Lord of the Rings, Appendix A, "The Númenorean Kings", "The Realms in Exile", "The Northern Line: Heirs of Isildur"
- J.R.R. Tolkien, Christopher Tolkien (ed.), Unfinished Tales, "The Disaster of the Gladden Fields"
- J.R.R. Tolkien, The Lord of the Rings, Appendix A, "The Númenorean Kings", "Eriador, Arnor, and the Heirs of Isildur"
- J.R.R. Tolkien, The Lord of the Rings, Appendix A, "The Númenorean Kings", "The Realms in Exile", "The Northern Line: Heirs of Isildur", note 4
- J.R.R. Tolkien, The Lord of the Rings, Appendix A, "The Númenorean Kings", "Gondor and the Heirs of Anárion"
- J.R.R. Tolkien, The Lord of the Rings, Appendix A, "The Númenorean Kings", "The Tale of Aragorn and Arwen"