A Wizard has a small torso and thin upper arms, but very wide, three-fingered forearms and hands. Its upper body and arms are covered by a high-collared, purple coat with a Heartless emblem on the chest and thin, white lining at its bottom. It sports a violet, wide-brimmed, conical hat with a thin, curled tip that resembles a stereotypical witch hat as well as the hat worn by Donald Duck in Kingdom Hearts Birth by Sleep.
It also wears a small, gold belt around its waist, over the coat, and a lavender robes underneath it that hides its feet and legs. Its head is a black sphere and it has glowing yellow eyes (though the eyes are hidden underneath the hat). A Wizard always holds a staff known as the Wizard's Relic. Unlike most Heartless, the Wizard did not gain a new coloration in Kingdom Hearts Final Mix.
The Wizard's name is a clear reference to wizards, referencing its magical prowess. The Wizard's name is also a reference to the job class from the Final Fantasy series, highlighting the Heartless's magical abilities and appearance.
Wizards are masters of magic, using Fire, Blizzard, Thunder, and Gravity spells. They cannot be harmed by most magic, and instead absorb the spells and go into a frenzy of casting. This can be countered if close, but will result in no damage.
It should be noted that Wizards are invincible while casting Thunder. Because of their immunity to magic in the first Kingdom Hearts, it is best to attack them physically. However, because all of their attacks are long-range, they will teleport if you get close, making a battle with these Heartless even more tedious. A couple hits with the Keyblade will destroy them.
Due to the Heartless invading many worlds, including Final Fantasy worlds, the Wizard Heartless may be created from Black Mages who lost their hearts. They have a similar design.