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:
Somehow I had the pleasure of never watching or knowing the plot of Terminator at all, so when I watched Terminator 2 for the first time a few years ago I had no idea that Arnold was the good guy going in. The twist 100% worked and it was fucking awesome when I released what was happening. Really wished they didn't spoil it in the trailer so most folks could get the wonderful experience I had.