Alastor Moody's magical eye

Alastor Moody's magical eye acts as a replacement eye for him after he lost his original one from a battle. It is a round, electric blue eye that he places into his empty eye socket. It can rotate 360 degrees in Moody's head, and allows him to see through anything, whether it be wood, Invisibility cloaks, or even the back of his head. It is this eye that earned Moody his nickname "Mad-Eye".

History
Sometime during the First Wizarding War, Moody lost his eye during his clash against Death Eaters, and had the magical eye as his replacement.

During 1994, before Moody was able to take his one-year post as Defence Against the Dark Arts teacher of Hogwarts School of Witchcraft and Wizardry, he was attacked and captured by Peter Pettigrew and Barty Crouch Jr., the latter of which disguised a him through Polyjuice Potion. Barty then took Moody's eye and leg for his own.

After Moody was freed and regained his eye, the eye tend to get stuck in mid-rotations at times due to Barty Crouch wearing it.

By the time of 1997, Moody was killed by Lord Voldemort during the chase of the Seven Potters. Moody's corpse was recovered by the Death Eaters, and his magical eye was taken by Dolores Umbridge, who used it to keep track of her subordinates in the Ministry of Magic.

When Harry Potter, Hermione Granger, and Ron Weasley broke into the Ministry, Harry found the eye and was disgusted by how it was used. He took it off its wall, which raised alarm. After the trio fled from the Ministry, Harry buried the eye under the oldest, most gnarled and resilient-looking tree he could find, and marked the grave with a small cross. With this, Moody was given a proper burial, even if not much.

Appearances

 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Deathly Hallows

Behind the scenes

 * In the books, the magical eye replaced Moody's right eye. In the films, it replaced his left.
 * In the books, the eye has been depicted to be simply to be inserted into his empty eye socket. In the films, it requires some special holder strapped around the socket.
 * In the fourth movie, the eye has shown to also have zoom-in capabilities.
 * It is unknown if this eye is unique to Moody, or if there can be some other wizards who can get one if they needed an eye-replacement.