Gandalf

In-universe, Gandalf is an immortal Maia (a spirit-origin class) who dwelt in Valinor and was known there as Olórin. He and other Maiar were sent to Middle-earth as the Istari with the mission to oppose the Dark Lord Sauron and to aid the peoples of Middle-earth. Though a spiritual being, he was embodied in a mortal form and thus could be slain; after his death fighting a Balrog his spirit wandered and he was 'sent back—for a brief time, until my task was done' and returned with altered rank and form.

Gandalf is usually described as grey-haired and grey-clad in his earlier guise, leaning on a staff and appearing older and less tall than some of the other Istari. After his death and return he is transformed to Gandalf the White, with changed clothing and status (the 'White Rider' appearance). He is associated with a staff and, by having received Narya from Círdan, thematically linked to a hidden inner flame and to fire-motifs.

As a Maia, Gandalf is an immortal spirit embodied to act in Middle-earth; his principal mode is counsel—'works mostly by encouraging and persuading'—and leadership by guidance and example. He bears Narya, the Ring of Fire, which 'enhanced' his spirit and associates him with fire used to succour hope and, in 'great need', as a weapon. He can take direct martial or magical action when required (notably his combat with a Balrog in Moria, where his body was destroyed but his spirit endured and was later returned). He does not seek dominion or power; his actions emphasize aiding and organizing free peoples against Sauron.