What is the name of J.R.R. Tolkien's wizard character who returns as Gandalf the White?

J.R.R. Tolkien's wizard character who returns as Gandalf the White is Gandalf the Grey.

Gandalf begins The Lord of the Rings as Gandalf the Grey, one of the Istari sent to Middle-earth to oppose Sauron. During the battle with the Balrog in Moria, he falls into the depths and fights the creature until both are killed. He is then restored and returns as Gandalf the White.

His change of color represents a major transformation in authority and purpose. Gandalf the White takes the place of Saruman, whose loyalty has failed, and becomes a leading force in the resistance to Sauron. Tolkien presents the event as a return from death rather than an ordinary change of clothing.

Saruman the White is a separate wizard, and Radagast the Brown is another member of the order. The Blue Wizards are two additional Istari whose eastern journeys are only briefly described in Tolkien's published narratives.