The cataclysmic Last Battle prophesied to be fought at the end of Arda, and in which its Doom or fate will be resolved. The prophecy of Dagor Dagorath - literally the 'Battle of Battles' - comes from various sources, most notably from Mandos the Doomsman of the Valar himself. Other versions of the prophecy were made by Andreth, a wise-woman among the Men of the House of Bëor, and while he does not make specific predictions, the Vala Ulmo also spoke of a fated 'End' that would bring about Arda's Doom and complete its making. Among the stars created by Varda at the time of the awakening of the Elves, the formation of the swordsman Menelvagor (or Orion as we know it today) was said to foretell the coming Last Battle.

According to the prophecies, the Dagor Dagorath will be brought about by the return of Morgoth, the first Dark Lord, who will return from his exile in the Outer Void. The events of the Last Battle will begin with Morgoth's destruction of the Sun and Moon (just as he destroyed the Two Trees and brought about the Darkening of Valinor long before). Eärendil bearing his shining Silmaril will then descend from the heavens to attack the Dark Lord, and will be joined by the warrior Vala Tulkas and by Manwë's herald Eönwë.³ According to some accounts, the great Dragon known as Ancalagon the Black will have a part to play in the battle (though other prophecies fail to mention the Dragon's appearance). Most versions also describe the great swordsman Túrin Turambar (as foretold among the stars by Menelvagor the Swordsman of the Sky) returning from the Halls of Mandos to join the conflict and ultimately defeat Morgoth.

We know little else for sure about the Dagor Dagorath, but there are scattered hints of the events surrounding it. For example, the warriors of Ar-Pharazôn who invaded Aman are said to be entombed in the Caves of the Forgotten until the time of the Last Battle, but what part they will play is unknown. We're also told that Manwë the Elder King will remain in his halls on Taniquetil until the Dagor Dagorath, though once again his role in the battle or its aftermath remains mysterious.

Events after the battle are even more mysterious than the Dagor Dagorath itself, but it's implied by various different sources that this will see the 'full-making' of the world. In that time the world will be remade as Ilúvatar originally intended, wiped clean of the corruptions of Melkor. The Dwarves, at least by their own account, will aid their creator Aulë in this remaking of Arda. Meanwhile the three Silmarils will be recovered from earth, sky and sea, and Yavanna will use them to bring back the Light of the Two Trees, now spreading not just through Aman, but across the whole of Arda.⁴

The various prophecies of the Dagor Dagorath all share one clear prediction: however it occurs, Melkor will lose. Prophecies of the Last Battle seem to have been well known, so surely Melkor himself had come across them, and this raises an obvious question: if his defeat is certain, why would he choose to take part in the Last Battle at all? Assuming the prophecies hold, perhaps this is the working of fate in action, or perhaps this represents Melkor's only hope, however slim, of escaping his exile in the Outer Void. However it comes about, it does seem that Melkor's participation in the Dagor Dagorath will ultimately and unavoidably lead to his destruction.