Alduin, or the World-Eater, as he is known to the residents of Skyrim, is an immensely powerful dragon. He is depicted as a malevolent force who destroys the world periodically, and the Nords believe that his reappearance heralds the end of time. He is the self-proclaimed First-Born of Akatosh and aspect of Akatosh. His name can be separated into "Al Du In", which means "Destroyer Devour Master".
He has a 50% resistance to fire and a 25% weakness to frost, and knows the Fire Breath, Frost Breath and Unrelenting Force shouts, as well as the Dragon Storm Call shout unique to him.