4. Jim Phelps - Mission: Impossible
The first Mission: Impossible boasts a brilliant yet controversial villain reveal in its third act, with the twist that legendary IMF director Jim Phelps (Jon Voight) is actually the film's big bad.
It initially appears that Phelps dies in a botched Prague mission at the start of the movie, along with several other members of his team.
But later on, it turns out that Phelps faked his own death and organised the murder of several of his own agents during the Prague op, having grown weary of the IMF and deciding to sell it out.
What made the reveal so fantastically shocking is that it played perfectly off audience expectations, given that Phelps was always a heroic character in the original TV series.
Many fans were consequently angered that Phelps' allegiance was shifted so drastically, but if nothing else, the fan belief that Phelps would never turn heel only made its eventuality that much more genius.