Elizabeth Greer Feldstein (born June 24, 1993) is an American actress. She first gained recognition for her starring roles in the comedy film Neighbors 2: Sorority Rising (2016), the comedy-drama film Lady Bird (2017), and the coming-of-age comedy film Booksmart (2019), the last of which earned her a nomination for the Golden Globe Award for Best Actress in a Motion Picture–Comedy or Musical.

Feldstein has appeared on the Broadway stage, making her debut as Minnie Fay in Hello, Dolly! (2017–18) and portraying the lead role of Fanny Brice in the first revival of Funny Girl (2022), a performance for which she earned a nomination for the Drama League Award for Distinguished Performance. In 2021, she portrayed Monica Lewinsky in the third season of the FX anthology series American Crime Story: Impeachment.