Gandalf the Grey, later known as Gandalf the White, also called Olórin (Quenya; IPA: [oˈloːrin]), Tharkun, and Mithrandir (Sindarin IPA: [miˈθrandir]), was a wizard, or Istar, sent by the West in the Third Age to combat the threat of Sauron. He joined Thorin and his company to reclaim Erebor from Smaug, convoked the Fellowship of the Ring to destroy the One Ring, and led the Free Peoples in the final campaign of the War of the Ring.
Gandalf was the wisest of the Maiar. He was first known as Olórin, and sometimes dwelt in the gardens of Irmo, and was the pupil of Nienna, who taught him wisdom and pity, and of Manwë and Varda. When the Valar decided to send the order of the Istari (also known as Wizards) to Middle-earth, to counsel and assist all those in Middle-earth who opposed the Dark Lord Sauron Manwë and Varda decided to include Olórin among the five who were sent.
When he arrived to Middle Earth he received Narya, the ring of fire, from Cirdan the Shipwright. Gandalf (Olorin) spent many centuries walking among the elves as a stranger, learning from them and teaching them. He later revealed himself as one of the Istari, and eventually became known as the wisest of and most powerful of that order. He joined the White Council, which was formed to investigate a dark power in Dol Guldur, of which Galadriel wanted him to become the leader, yet Saruman came to lead the Council instead of him.