Rhett Butler, revealing to Scarlett that he has eavesdropped on her entire desperate attempt to keep Ashley Wilkes from marrying his cousin, and witnessed her destruction of a harmless vase: "Has the war started?" Topped a few seconds later, when Scarlett tells him he is no gentleman, and he responds, "And you, Miss, are no lady."
Katie Scarlett O'Hara, a crying, crumpled heap in the dirt, hungry, humiliated, everything she's known broken, reduced to clawing dead potatoes with her fingers from the ground, begins to stand up:
"As God is my witness, as God is my witness, they're not going to lick me. I'm going to live through this and when it's all over, I'll never be hungry again. No, nor any of my folk. If I have to lie, steal, cheat or kill. As God is my witness, I'll never be hungry again!"
Scarlett waltzing delicately into prison, wearing the finest dress ever seen in the South, despite being a few years out of fashion, and despite the fact that she barely has money to buy food. The fabric of the dress looks very much like the late curtains at Tara...
Scarlett shooting the Yankee soldier right between the eyes. No one invades Tara when Scarlett is there.
Melanie, who has risen from her sickbed and is holding a sword she can barely lift, sees the dead Yankee and says, "You killed him!... I'm glad you killed him."
Then Scarlett and Melanie, two "delicate flowers" raised in the most gentle of environments (at least until the war started), calmly search through the dead Yankee's belongings, then proceed to cover up the evidence of the murder (including getting rid of the body) by themselves, without even letting anyone in the family know what had happened. Melanie even effortlessly comes up with a plausible lie when Scarlett's father and sisters heard the gunshot.
The first time we see Rhett in the movie. He doesn't do anything but crack his Clark Gable smile while looking up at Scarlett yet he looks... awesome.
Scarlett facing off against the Yankees when they try to take Wade's sword in the book.
Melly running back to Tara to help Scarlett put out the fire started by the Yankees. Even Scarlett has to admit that Melly is always there when you need her.
Mammy ever so delicately pointing out to Scarlett that she "ain't never gonna be eighteen inches agin."
The impromptu ruse Rhett thinks up to make the Yankees think the gentlemen of Atlanta were not involved in the Shantytown raid. Especially awesome is how well Melly plays along.
This leads to a funny bit a little later when Rhett admits to Melanie that he did hide the gentlemen in Belle Watling's "sporting house", and Melanie huffily refuses to believe it.
Will Benteen skillfully removing the "eulogies from the neighbors" part of Gerald's funeral in order to protect Suellen from their neighbors' wrath.
Mammy revealing she understands that Scarlett plans on stealing Frank Kennedy from Suellen in order to get the money for the taxes on Tara - and giving Scarlett her full support.
"Frankly, my dear, I don't give a damn." Now that's a line worth waiting four hours for.
A bit of context: after years upon years of having her own way and essentially stepping on people, Scarlett finally gets told off. The line is Rhett cementing that, no matter what she tries, Scarlett cannot win this one.
Real life Moment Of Awesome - Hattie McDaniel becoming the first African-American to win an Oscar, a good fifteen years before the Civil Rights Movement.
An incensed Clark Gable threatening to boycott the movie's Atlanta premiere when he heard Hattie McDaniel was not welcome because of segregation. Even better - it was McDaniel herself who convinced Gable to change his mind and attend the premiere.
Gable and McDaniel had known each other before the film and were friendly for the rest of their lives. One can't help but feel this informs their performance, and is partly the reason for Rhett's fondness for Mammy in film.