Klaatu: [after reading the Gettysburg Address at the Lincoln Memorial] Those are great words.
Klaatu: [turns to look at the statue of Lincoln] He must have been a great man.
Bobby Benson: Well sure.
Klaatu: [walking out of the memorial, then turning to look at Lincoln again] That's the kind of man I would like to talk to.

Klaatu: I am fearful when I see people substituting fear for reason.

Klaatu: I won't resort to threats, Mr. Harley. I merely tell you the future of your planet is at stake.

Klaatu: I'm worried about Gort. I'm afraid of what he might do if anything should happen to me.
Helen: Gort? But he's a robot. Without you, what could he do?
Klaatu: There's no limit to what he could do. He could destroy the Earth.

Klaatu: Perhaps before deciding on a course of action, you'd want to know more about the people here - to orient yourself in a strange environment.
Mrs. Barley: There's nothing strange about Washington, Mr. Carpenter.
Klaatu: A person from another planet might disagree with you.
Mrs. Barley: If you want my opinion, he came from right here on Earth. And you know where I mean.
Mr. Krull: They woudn't come in spaceships, they'd come in airplanes.
Mrs. Barley: I woudn't be too sure about that.

Klaatu: We have come to visit you in peace and with goodwill.

Bobby Benson: [indicating grave marker during a visit to Arlington] That's my father. He was killed at Anzio.
Klaatu: Did all those people die in wars?
Bobby Benson: Most of 'em. Didn't you ever hear of the Arlington Cemetery?
Klaatu: No, I'm afraid not.
Bobby Benson: You don't seem to know much about anything, do you, Mr. Carpenter?
Klaatu: Well, I'll tell you, Bobby, I've been away a long time. Very far away.
Bobby Benson: Is it different where you've been? Don't they have places like this?
Klaatu: Well, they have cemeteries, but not like this one. You see, they don't have any wars.
Bobby Benson: Gee, that's a good idea.

Bobby Benson: [to Klaatu] I like you Mr. Carpenter, you're a real screwball!

Bobby Benson: Department of Commerce. She's a secretary. They have a man they call the Secretary, but he isn't at all. My mother's a *real* secretary.

Helen: Gort! Klaatu barada nikto!