Who Left the Biggest Impression in Their Acting Debut?

Some actors work their way up to fame with bit role after bit role, while others steal the spotlight their very first time on the screen. This list is dedicated to those first-time out-of-the-gate scene-stealers.

Which of these acting debuts left the biggest impression on you?

To keep this group of actors more special, I am not including actors who were previously credited for appearing in TV shows or TV movies prior to their 'big film debut'; the debut movie needs to have at least 2,000 votes for the actor to be included; and the actor needs to have at least appeared in one later credited role (otherwise they might be one-hit wonders).

Discuss here: http://www.imdb.com/board/bd0000088/thread/224756759