"I understand. You found paradise in America, you had a good trade, you made a good living. The police protected you and there were courts of law. You didn't need a friend like me. But, now you come to me, and you say: 'Don Corleone, give me justice.' But you don't ask with respect. You don't offer friendship. You don't even think to call me Godfather. Instead, you come into my house on the day my daughter is to be married, and you ask me to do murder for money." - The Godfather

Gotta be the most "bring you back down to earth" quotes you can get.

"You are privy to a great becoming, but you recognize nothing. To me, you are a slug in the sun. You are an ant in the afterbirth. It is your nature to do one thing correctly. Before me, you rightly tremble. But, fear is not what you owe me. You owe me awe." 

- Francis Dolarhyde (Red Dragon)

Well, the one that made me think the most was the one on the blimp scene on Scarface.

"THE WORLD IS YOURS..."

This was the high point for TM, he finally became the ONE drug lord in florida. He was there, bloody, recovering from a bullet, had killed frank and was waiting for elvira to pack her things and go with him. And the music is top notch, it completes the scene.

Its not a spoken quote, but its deffo a powerful one.

Hated the movie Con Air but I still love the line where John Malkovich's character Cyrus is mad at one of the other convicts. That other convict is standing in fuel and Cyrus has a lit cigarette in his hand. The other guy says "Cy", begging for mercy and JM says "Onara" making the total "sayonara" before flicking his cigarette into the fuel and killing the other guy.

The "Here comes the pain! of Carlito's Way, it's something that sometimes comes up in my mind. Especially when I'm mad with someone XD

"It's alive! It's alive! In the name of God! Now I know what it's like to be God!"

The  full line  was cut because it was considered blasphemous against God.

It was  cut down to "It's alive! It's alive" 

From Frankenstein 1931

"Get me a chocolate donut with some of those little sprinkles on top.... while you're thinking."  -Sammy Gerard The Fugitive 1993

"Shampoo is better, it cleans the hair. No, Conditioner is better it leaves the hair silk smooth. UH UH UH UH *Bottle fight* STOP LOOKING AT ME SWAAAN." 

From the movie Sugar Hill. 

"Look Lolly, I think we need to call a truce. You don't hit my men, I won't hit yours. You don't hurt my brother... and I won't take your whole family. We'll work it out so you can get a piece of the action. Ok, chump? I mean champ."

“We’re soldiers. Soldiers don’t go to hell. It’s war. Soldiers kill other soldiers. We’re in a situation where everyone involved knows the stakes and if you are going to accept those stakes, you’ve got to do certain things. It’s business.”

Tony Soprano

so one of the opening scenes in 'way of the gun'

it's a tad misogynistic but it's funny as hell

a woman shouts from a crowd at 2 guys near a car and one turns round a says

'shut that cunts mouth or i'll come over there and fuck start her head'

made me lol

English, Motherfucker, do you speak it?

But that whole movie is a goldmine of memes and quotes and whatnot :D

 I... I used to make long speeches to you after you left.
I used to talk to you all the time, even though I was alone.
I walked around for months talking to you. Now I don't know what to say.
It was easier when I just imagined you. I even imagined you talking back to me. We'd have long conversations, the two of us. It was almost like you were there. I could hear you, I could see you, smell you. I could hear your voice.
Sometimes your voice would wake me up. It would wake me up in the middle of the night, just like you were in the room with me. Then... it slowly faded. I couldn't picture you anymore.
I tried to talk out loud to you like I used to, but there was nothing there. I couldn't hear you. Then... I just gave it up. Everything stopped. You just... disappeared. And now I'm working here. I hear your voice all the time. Every man has your voice.

from the movie "Paris, Texas "

My name is Antonio Montana Man,

political refugee from Cuba,

and I want my fucking human rights!

-Scarface

"Will someone please pass me the fucking asparagus!!"

-American Beauty

"sometimes there is no difference between damnation and salvation-The Green Mile

"Are you happy, Stephen?" It's the question Christine Palmer asked me at her wedding. I said "Yes, of course I'm happy. I'm a sorcerer with the power of gods. What man wouldn't be happy?" Then, I came back to this goddamn haunted house, sat down, and wondered why I'd lied." 

- Sinister Strange (Doctor Strange In the Multiverse of Madness)

“Say hello to my little friend!”

- Scarface

“Ah, how shall I do it? Oh, I know. I’ll turn him into a flea, a harmless, little flea, and then I’ll put that flea in a box, and then I’ll put that box inside of another box, and then I’ll mail that box to myself, and when it arrives, I’ll smash it with a hammer! It’s brilliant, brilliant, brilliant, I tell you! Genius, I say!” — Yzma