Sydney Bernice Sweeney (born September 12, 1997) is an American actress. She gained early recognition for her roles in Everything Sucks!, The Handmaid's Tale, and Sharp Objects in 2018. She received wider acclaim for her performances in the drama series Euphoria (2019–present) and the first season of the anthology series The White Lotus (2021), both of which earned her nominations for Primetime Emmy Awards.

In film, Sweeney appeared in Quentin Tarantino's Once Upon a Time in Hollywood (2019) and later had leading roles in the drama film Reality and the romantic comedy Anyone but You, both in 2023. In 2024, she played Julia Cornwall in the superhero film Madame Web and starred in the horror film Immaculate.