I hope she'll be a fool, that's the best thing a girl can be in this world -- a beautiful little fool.
~ Daisy describing her daughter.
Daisy "Fay" Buchanan is the villainous tritagonist in The Great Gatsby.
She symbolizes the amoral values of the aristocratic East Egg and was partially inspired by Fitzgerald's wife Zelda Fitzgerald.
She was portrayed by Mia Farrow - who also played Mrs. Baylock in the 2006 remake of The Omen - in the 1974 film adaptation and by Carey Mulligan in the 2013 film adaptation.
Role in The Great Gatsby
She was the wife of the novel's principal antagonist Tom Buchanan and the mother of Pammy Buchanan. She was also the cousin of Nick Carraway, the novel's narrator. Five years ago, she met the young James Gatz when he was about to leave to fight in World War I. Gatz fell in love with her and wanted to marry her. However, he didn't have the money for it. He asked her to wait for him and she agrees to. However, in 1919, she grew tired of waiting and married into the Buchanan family. Gatsby then spent the remaining years of his life trying to win her back.
When Gatsby asked Nick to invite Daisy over for tea, she immediately thought of using Gatsby's love for her to get back at her husband for cheating on her. However, she is unwilling to leave Tom because of his status as the "old money," and so she sides with him thus betraying Gatsby and shattering his dreams.
After Tom and Gatsby's confrontation at the Plaza, Daisy takes the wheel of Gatsby's car and rides away with him. She then sees Myrtle Wilson, Tom's mistress, running out towards the car, and runs her over by accident. Gatsby, still disillusioned by his love for her, takes the blame for Myrtle's death, and Daisy lets him have it without any second thought.
The next day, George Wilson arrived at Gatsby's home and fatally shot him while he was in the swimming pool. Nick then tried to arrange a funeral service for his friend. Though hardly anyone came. The final nail to Gatsby's coffin was that Daisy, his perceived lover, didn't try to go to his funeral nor wrote a message or sent flowers. This permanently shows that she never cared for Gatsby and used his love for her to her advantage. Nick soon concluded that she and her husband were careless people who smashed things up and retreated while leaving behind their money having other people cleanup the messes they made.
At first glance, Daisy appeared to be a tragic figure who was displayed as pure and beautiful. However, this is only what Gatsby thought she was like. In reality, she was a very vain woman who cared for nothing other than money. She even seemed indifferent about her daughter.
For example, when Nick asked her about her daughter, she told him that she ate and slept and she also wished that she would be a beautiful fool when she grew up, thinking that she'd be more happy that way. She is sardonic and somewhat cynical, and behaves superficially to mask her pain at her husband's constant infidelities. She also seemed to have sociopathic symptoms. For example, she could fake her feelings for Gatsby and ran Myrtle down without any remorse.
However, she did seem to genuinely like her cousin Nick to a certain extent. You could also say that she's doomed to a loveless marriage due to her insatiable love of money.