I am not sure exactly what you mean, but I will answer for the two possibilities.
In the movies/books The White Wizard joins ranks with Sauron and leaves the Elves, Humans, Hobbits, Dwarves, and various other races on the "good guys." Gandalf, being the second strongest wizard, takes up the title of The White Wizard after being killed in mortal combat by the Balrog, he is then reborn.
Why they chose to make Gandalf caucasian, I do not know, it is probably just because that actor was best suited for the role of Gandalf.
Gandalf was originally known as Gandalf the Grey. After his rebirth, he became Gandalf the White in replacement of Saruman. Gandalf the Grey and after his resurrection he became Gandalf the White.
He is part of the fellowship of the ring. He acted as their guide. He was gandalf the grey and then he returns as gandalf the white in 'the two towers.' To add to that he is awesome!
The basic background behind the character Gandalf from the Lord of the Rings Series is that he is a wizard. He is initially called Gandalf the Grey but after resurrecting he is then referred to Gandalf the White.
Grey And White
Gandalf was originally Gandalf the Grey, but after he was reborn he became Gandalf the White. He was played by Sir Ian McKellen in the popular movie series. Saruman was the white wizard in the Fellowship of the ring. Gandalf was the grey wizard. Since Gandalf fell in Moria, he was sent back, thus given a different color. So Gandalf became Gandalf the White and Saruman was left without a color and defeated.
Saruman #1, white (later fallen, and unranked). Gandalf #2, grey (later white and #1). Radagast #3, brown. Morinehtar #4, blue. Rómestámo #5, blue.
Grey. Hence, "Gandalf the Grey." -sam-is-my-hero-
Gandalf Three wizards played a direct part in The Lord of the Rings (movies and books): Gandalf the Gray (and later the white) Saruman the White (and we know what happened to him) Radagast the Brown -- birds, trees flowers were his specialty. Two others were mentioned obscurely. They were the Blue Wizards, Alatar and Pallando.
There are a sufficent number of wizards in literature and myth that I would need to know which set of stories or mythologies you are referring to. If you are referring to the Lord of the Rings, for example, you have Gandalf the Grey, Gandalf the White, Saruman (all different manifestations of Gandalf), and Sauron.
Gandalf the White is overwhelmingly a force for good.
Could you possibly mean Gandalf? Then yes, Crown Princess Gandalf the Grey of Terabithia.
His known names, usually given to him by various peoples: -Gandalf ("Elf of the Wand", though he is not an elf) by various peoples. Titled as "Gandalf the Grey" and "Greyhame" or later "Gandalf the White". -Mithrandir (Sindarin "Grey Pilgrim", "Grey Wanderer") from the Elves, also used by the Men of Gondor. -Tharkûn, from the Dwarves. -Incánus, from somewhere in the South. -Olórin, which he was called in the West in Aman. He has also been called various other things, some of therm derogatory, although they are not used as proper names.