God as my witness, these are the most acclaimed actresses on the planet.
1. Vivien Leigh in "Gone With the Wind" (1939) and "A Streetcar Named Desire" (1951)
Vivien Leigh. She almost looks like an Oscar to me at this point.
Though no other role of hers compares to these two, it doesn't matter. Scarlett O'Hara is an astoundingly big and evil character. I did say evil. She's an 1860s Lucy Van Pelt-type sociopath who thinks the Civil War is a battle between her own narcissism and more money. She spends most of the movie wanting to make her mansion pretty because this pesky war knocked over her boudoir. She is aggressively shallow, and Vivien Leigh could not be more pungently self-absorbed. Fabulous.
Then there's Blanche in "Streetcar," my choice for the most important performance in cinema. Vivien infuses Blanche's fragility with pitiful (purposeful) artificiality and simply seems to come undone at the very presence of Stanley Kowalski (Marlon Brando). She is lithium-tinged and deadly misinformed about herself. As Brando ushered us into a new, bolder acting style, Leigh summoned the mannered affectations of a Joan Fontaine-type ingenue and let them shrivel and explode in front of us. Blanche DuBois is the most magnificent of our tragic cinematic figures, a woman whose desperation only found fascinating ways to reveal and hide itself.