Gandalf
Originally called Olórin, he was accounted as the wisest of the Maiar. He was a Maia of Manwë and Varda. He also served under two other Valar, such as Irmo and Nienna. 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.