Gandalf, who is often referred to as Mithrandir, is a very wise and powerful wizard. Before Gandalf set off for Middle-Earth he was given the Ring of Fire, Narya, by Cirdan. When he arrived at Middle-Earth he spent much of his time roaming and learning the various races of people, creatures and places throughout Middle-Earth. This experience proved valuable for Gandalf, as he became an expert on Middle-Earth which greatly assisted him during the War of the Ring. In The Hobbit Gandalf helped form the party, which included Bilbo Baggins, that went on to defeat the dragon Smaug.

Years later at Bilbo Baggins 111th birthday Gandalf discovered the One Ring was being used and kept by Bilbo. Gandalf was able to convince Bilbo to leave the ring behind when Bilbo had made up his mind to leave the Shire. Knowing the power of the One Ring Gandalf knew that he attempted to take the ring for himself it would over take him and create an ustoppable power. He entrusted it to Frodo to have it taken to Rivendell and ultimately entrusted it to Frodo to be destroyed. He was vital in forming the Fellowship of the Ring but fell during his battle with Balrog in the Mines of Moria.

Gandalf's importance was too great and his spirit was sent back and turned Gandalf the Grey into Gandalf the White an even more powerful wizard. His role during the War of the Ring was of extreme importance. He helped free King Theoden of Saruman's spell, assisted in the victory at Helm's Deep, turned Saruman into a powerless wizard and took charge of Minas Tirith during Sauron's attempt to siege and destroy Gondor. There are many more things that Gandalf did, he's great knowledge makes him one of the most important people on Middle-Earth.

Other Info: Gandalf's horse's name is Shadowfax. The sword he uses is known as Glamdring.