There's also a great scene in MI: Ghost Protocol, where they have to go up the outside of the Burj Khalifa and it suddenly dawns on Ethan Hunt that he's the one that has to do it (the rest of the team have other jobs). And he walks over to the open window and looks out and the colour drains from his face and the fear and panic set in. And then he tries to talk his way out of it. 

A brilliant, humanising scene for a "superhero" character and beautifully played by Cruise.