"Smile, you son of a bitch." Brody to the shark, Jaws.

"Yipee Ki-Yay, Motherfucker." John McClane to Hans Gruber, Die Hard.

"Look in your heart!" "What heart?"
- John Tutturro and Gabriel Byrne, Miller's Crossing (even better if you've seen the set up scene).

"Don't you want to hear my last words?"
"I just did."
- Danny DeVito and Gene Hackman, Heist (classic Mamet).

"Dodge this!" Trinity to an Agent, The Matrix.

although he doesn't actually say it when he makes the killing blow, Inigo Montoya from Princess Bride has the most epic example of killing dialogue:

"Hello, my name is Inigo Montoya. You killed my father. Prepare to die."

also, even though i hate godfather part iii, the line by andy garcia when he pops joey zasa is classic.

"heya joe! *bang bang* *bang* zasa."

the way he says "zasa" is perfect. like it's a punchline. zasa.

Deserve's got nothing to do with it. - William Munny, Unforgiven

Wrong Wade, there was a way.
- Gail Hartman, The River Wild

Fuck you too!
- McReady, The Thing

You'll have to speak a little louder if ya want your friend to hear ya.
- Gypsy, Snatch

Did he sound anything like that?
- Elliot Ness, The Untouchables

Anything from Dirty Harry.

I know what you're thinking. Did he fire five shots or six....

And a few I can't think of the movie for...

Who said anything about arresting you?

"...and you will know my name is the Lord when I lay my vengeance upon thee!"

- Jules
Pulp Fiction
Prior to emptying his 9mm Glock into Brett

Well, c'mon, SOMEbody had to toss this one out, right?

I didn't put the WHOLE quote up.... if you need it, just consult your nearest bible.

You know the chapter and verse....

"dyin ain't much of a way to make a livin." -- clint eastwood as the outlaw josey wales

my fav (although a bit long):
I know what you're thinking. "Did he fire six shots or only five?" Well, to tell you the truth, in all this excitement I kind of lost track myself. But being as this is a .44 Magnum, the most powerful handgun in the world, and would blow your head clean off, you've got to ask yourself one question: Do I feel lucky? Well, do ya, punk?

Matrix: Remember, Sully, when I promised to kill you last?
Sully: That's right, Matrix. You did.
Matrix: I lied.

Arnold Schwarzenegger, Commando