Avada Kedavra is the Killing Curse from the Harry Potter books and films, one of the three Unforgivable Curses and the signature spell of Lord Voldemort and other Dark wizards. In the story it causes instant death, usually accompanied by a flash of green light, which made it instantly recognisable to audiences. As clips from the films spread online, editors began lifting the incantation for short videos, using it as a shorthand for deleting, defeating, or shutting something down. That simple, dramatic meaning has kept it popular in memes, gaming edits, and reaction videos long after the films.