Are there any lesser-known but significant wizard comic characters worth exploring?

Yes, several. Doctor Voodoo (Jericho Drumm) from Marvel Comics, who became Sorcerer Supreme and is a master of Houngan magic, offers a unique cultural perspective. Klarion the Witch Boy from DC Comics is a powerful and chaotic magic-user from another dimension. Timothy Hunter from DC/Vertigo's 'Books of Magic' is a young boy prophesied to become the greatest magician, providing a rich narrative for magical discovery and responsibility. These characters offer diverse takes on magic and wizardry.