"Cast Away". Tom Hanks, when he loses Wilson, especially. I also appreciate the fact that Zemeckis left the entire movie literally unscored, so there wasn't any cliche "sad music" at times of loss.
"The Pianist", also. Adrian Brody is incredible on his own, but to watch him, and his characters resolve throughout the movie, given all his incredible hardships..wow. I've never wanted to reach out and help someone so bad.
"Life As a House". Kevin Kline and Hayden Christensen's chemistry was unreal. Easily their best movie, respectfully, and a powerful one.
"Green Mile". John Coffey and Mr. Delacroix were two of the richest, most likeable characters ever, and to lose them both, as innocent as they were was heartbreaking. It's also one of those movies where you wish you could pummel someone, like Percy.