A well-camouflaged villain
Gellert Grindelwald is a character whose presence is discovered at the end of the movie Fantastic Beasts but who had actually been there during the whole movie. Indeed, thanks to the Polyjuice potion, he had taken the appearance of Percival Graves, a member of the American Ministry of Magic, which allowed him to easily be part of the investigation to solve the mystery of the strange phenomena taking place in New York but with his own goals quite different from those of the government. Indeed, a kind of black shadow is devastating some parts of the city and an obscurus is suspected to be responsible. An obscurus is a very powerful creature created by a wizard whose magic has been suppressed for too long and who expresses himself in this way. This obscurus is very powerful because, while children whose magic is suppressed long enough to create an obscurus do not survive long, Credence, the one who created this one, is already almost grown. While the Ministry of Magic wants to find him to stop him from acting, Grindelwald is interested because he wants wizards to come out and not live hidden from other humans.