The Elder Scrolls V: Skyrim - Dawnguard

The emergence of a prophecy called the Tyranny of the Sun that coincides with the Dragonborn has driven vampires to become more brazen in attacking mortal folk, throwing Skyrim into greater turmoil. An old order of vampire hunters called the Dawnguard is reformed to help suppress the vampire menace, as the fate of the world is threatened by the children of Coldharbour's desire to blot out the sun forever.