The Day the Earth Stood Still (1951)

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.

Helen: Gort! Klaatu barada nikto.

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.

Reporter: I suppose you are just as scared as the rest of us.
Klaatu: In a different way, perhaps. I am fearful when I see people substituting fear for reason.

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.

Secretary: The phone doesn't work.
Mr. Krull: Well then call the phone company.
Secretary: But... the phone doesn't work.

Klaatu: Gort: Barenga.

Helen: I thought you were.
Klaatu: I was.

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

Klaatu: Gort! Deglet ovrosco.

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

Helen: Now, you didn't really see a spaceship, but you thought you did.
Bobby Benson: I'd never call you a liar.

Army physician: I don't know whether to get drunk or quit the practice of medicine.

Klaatu: You have faith, Professor Barnhardt?
Barnhardt: It isn't faith that makes good science, Mr. Klaatu, it's curiosity. Sit down, please. There are several thousand questions I'd like to ask you.

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

Bit Man: They're here! They're here! They've landed! Over on the mall! They've landed.