Tom Ripley: I always thought it'd be better to be a fake somebody than a real nobody.

Tom Ripley: If I could just go back... if I could rub everything out... starting with myself.

Tom Ripley: You're the brother I never had. I'm the brother you never had. I would do anything for you, Dickie.

Tom Ripley: Nothing is more naked than your handwriting. See how nothing's quite touching the line? That's vanity.

Marge Sherwood: I don't believe a single word you've said.
Tom Ripley: You're shivering, Marge. Look at you, Marge. Can I hold you? Will you let me hold you?

Tom Ripley: Well, whatever you do, however terrible, however hurtful, it all makes sense, doesn't it, in your head. You never meet anybody that thinks they're a bad person.

Peter: Good things about Mr. Ripley? Could take some time. Tom is talented. Tom is tender... Tom is beautiful... Tom is a mystery. Tom is not a nobody. Tom has secrets he doesn't want to tell me, and I wish he would. Tom has nightmares. That's not a good thing. Tom has someone to love him. That is a good thing. Tom is crushing me. Tom is crushing me... Tom, you're crushing me!

And my favorite:
Tom Ripley: And that's the irony, Marge. I loved you. You may was well know it, Marge: I loved you. I don't know... maybe it's grotesque of me to say this now, so just write it on a piece of paper or something and put it in your purse for a rainy day. 'Tom loves me.' 'Tom loves me.'