More often than not a big-time A-list actor more than likely got his or her start by making a brief appearance in another film without you knowing who that person was. At the time they were probably just an up and coming actor filling the shoes of a role that was needed to complete said film. Or maybe a well-known actor made a cameo in a project to give it more recognition. Then there are the rare times that certain supporting roles fly over your head because you don't identify the actor until long after the film ends.
Making a list of some of the more uncommon roles that fall into this category was fairly challenging. These aren't just the first actors, parts, and films that come to mind. Things that are too obvious like Stan Lee's cameos in Marvel comic book movies, Bruce Campbell in Sam Raimi's "Spider-Man" trilogy, or Johnny Depp in "21 Jump Street" are fun, but a little too easy since the audience got to the point where they expected those. This list is handpicked and hopefully a little less straightforward.