Vindictus Viridian was a wizard and the author of the textbook Curses and Counter-Curses. While not mentioned in the original novels, information from supplementary materials portrays him as a duellist from the 18th century who vanished under mysterious circumstances. He is rumored to have been a Dark Wizard, though this is unconfirmed.
Little is known about the life of Vindictus Viridian. He authored the book Curses and Counter-Curses, which suggests he possessed considerable knowledge of both offensive and defensive magic. According to his Famous Witches and Wizards Card, Viridian lived and died in the 18th century. He was known to frequent the duelling clubs of London. His life ended abruptly when he vanished following a duel. Rumors circulated that a curse had transmogrified him into a pot plant, though the truth of this remains unknown (video game).
There is no known description of Vindictus Viridian's physical appearance or personality. His name and the subject of his book suggest he may have had a vindictive or confrontational nature, but this is purely speculative.
No information exists regarding Vindictus Viridian's family, friends, or specific enemies. The identity of the opponent in his final duel is unknown.
Vindictus Viridian does not appear in the seven original Harry Potter novels. His existence is established through supplementary materials. On Pottermore (now Wizarding World), his book Curses and Counter-Curses is listed on the first-year equipment list for Hogwarts School of Witchcraft and Wizardry. This contradicts the list provided in Harry Potter and the Philosopher's Stone, which lists the required Defence Against the Dark Arts book as A Guide to Self-Protection by Quentin Trimble. Viridian also appears on a Famous Witches and Wizards Card in the video game adaptations of Harry Potter and the Philosopher's Stone and Harry Potter and the Chamber of Secrets. The card provides the few biographical details that are known about him, including his death in the 18th century and the rumor that he was transmogrified into a pot plant.