As a wizard and the bearer of a Ring of Power, Gandalf has great power, but works mostly by encouraging and persuading. He sets out as Gandalf the Grey, possessing great knowledge, and travelling continually, always focused on the mission to counter the Dark Lord Sauron. He is associated with fire, his ring being Narya, the Ring of Fire, and he both delights in fireworks to entertain the hobbits of the Shire, and in great need uses fire as a weapon. As one of the Maiar he is an immortal spirit, but being in a physical body on Middle-earth, he can be killed in battle, as he is by the Balrog from Moria. He is sent back to Middle-earth to complete his mission, now as Gandalf the White and leader of the Istari.
Tolkien once described Gandalf as an angel incarnate; later, both he and other scholars have likened Gandalf to the Norse god Odin in his "Wanderer" guise. Others have described Gandalf as a guide-figure who assists the protagonist, comparable to the Cumaean Sibyl who assisted Aeneas in Virgil's The Aeneid, or to Virgil himself in Dante's Inferno; and as a Christ-figure, a prophet.