Ancalagon

The mightiest of Morgoth's winged dragons, loosed from Angband against the host of the Valar at the end of the War of Wrath. Even that mighty army was driven back by the onset of Ancalagon and his vassals, but Eärendil came through the sky in his ship Vingilot to do battle with the dragon armada, and he was aided by Thorondor and the Eagles. They fought for twenty-four hours, until Eärendil at last slew Ancalagon, who fell on the mountains of Thangorodrim and destroyed them in his ruin.