Avada Kedavra is one of the three Unforgivable Curses in Harry Potter, first introduced in the books by J.K. Rowling and made widely recognisable by the films, where Lord Voldemort and other Death Eaters use it as an instant, fatal spell. Its distinctive shouted incantation and green light became shorthand for overwhelming power in fan culture. Clips of the curse spread through Harry Potter edits, gaming videos and reaction memes, where it now signals a decisive, over-the-top defeat rather than literal violence, keeping it popular long after the films ended.