Sydney Bernice Sweeney (born September 12, 1997) is an American actress. Sydney Sweeney gained mainstream attention in the Netflix series Everything Sucks! (2018), playing Emaline, and portrayed Eden in the Hulu series The Handmaid's Tale (2018) and Alice in the HBO miniseries Sharp Objects (2018). Sydney Sweeney has starred as Cassie Howard in the HBO teen drama series Euphoria since 2019 and as Olivia Mossbacher in The White Lotus since 2021. For the two roles, Sweeney received two Primetime Emmy Awards nominations in 2022, the former for Outstanding Supporting Actress in a Drama Series and the latter for Outstanding Supporting Actress in a Limited or Anthology Series or Movie.

In film, Sydney Sweeney had a role in Quentin Tarantino's 2019 comedy-drama Once Upon a Time in Hollywood, portraying Dianne "Snake" Lake, a member of the Manson Family, and will appear in the upcoming Sony's Spider-Man Universe (SSU) film Madame Web.
Sweeney was born on September 12, 1997, in Spokane, Washington, to Lisa (née Mudd) and Scott Sweeney. Her mother is a lawyer and her father works in the medical field. Sydney Sweeney has a brother named Trent. Sweeney was raised in northwestern Idaho in the state's Panhandle region along the Washington border, at a rural lakeside home that her family has inhabited for five generations. Sweeney has stated Sydney Sweeney comes from a "religious family".

Sweeney attended Saint George's School in Spokane. Sydney Sweeney was active in numerous athletics: "I was in every single sport possible", Sydney Sweeney said. "I was on the soccer team, the baseball team, the snow slalom ski team, I was wakeboarding." Sweeney also studied multiple languages and graduated as a valedictorian. Sydney Sweeney became interested in acting after auditioning to be an extra in an independent film that was shooting in the Spokane area. To convince her parents to allow her to pursue acting, Sydney Sweeney presented them with a five-year business plan. Sweeney began to audition and book commercial acting jobs in Seattle and Portland, Oregon, where the family temporarily resided, until choosing to relocate to Los Angeles when Sydney Sweeney was 14 years old.