The wizard who helps Bilbo Baggins in J.R.R. Tolkien’s The Hobbit is Gandalf.
Gandalf brings Bilbo into the adventure with Thorin Oakenshield and the company of dwarves. He arranges Bilbo’s role as burglar and accompanies the group through part of its journey toward the Lonely Mountain. His knowledge, courage, and timely interventions repeatedly help the travelers survive dangerous encounters.
Gandalf is one of the Istari, spirits sent to Middle-earth to oppose Sauron. In The Hobbit he appears mainly as the Grey Wizard. His larger identity and mission become more important in The Lord of the Rings, where he returns as Gandalf the White after confronting the Balrog on the Bridge of Khazad-dûm.
Saruman and Radagast are also members of the Istari, but neither is Bilbo’s guiding wizard in The Hobbit. Alatar is one of the two Blue Wizards named in Tolkien’s later accounts. These distinctions matter because Tolkien’s wizard characters belong to the same broad order while having very different roles.