Everyone loves that moment when they recognize one of their favorite actors in a surprise cameo. But for every noticeable appearance, countless cameos slip by viewers. Even the most eagle-eyed film fans can't always catch the actors behind certain CGI and masked characters, because the people portrayed are intentionally unrecognizable.
Actors make cameo appearances for many reasons. Sometimes, it’s a favor to a friend, or a desire to work with a particular director. Other times, actors want a part in a massive movie franchise - which is why many unrecognizable and uncredited cameos come from blockbuster franchises like Star Wars and the Marvel Cinematic Universe. Most people will do anything to get their face in one of these films, even if it's not their own face.