I'll start.
Did you know that Wil "Wesley Crusher" Wheaton's first credited acting role was Martin on the Secret of NIMH animated film? That was probably the last time he sounded assertive and tough in an acting role too, and he was both a little kid and a mouse. :rat-salute:
Replying to keep Star Wars all in one spot: after the trash compactor scene of A New Hope as some storm-troopers are walking into the room one of them is slightly taller than the rest and hits his head on the doorframe.
Daniel Craig has a small part in The Force Awakens - he's the weak-minded trooper who releases Rey while she's shackled to that torture chair thingy.