Sadie Elizabeth Sink (born April 16, 2002) is an American actress. She began acting at age seven in local theater productions, and played the title role in Annie (2012–14) and young Queen Elizabeth II in The Audience (2015) on Broadway. She made her television debut in a 2013 episode of The Americans and her film debut in the sports film Chuck (2016).

Sink had her breakthrough portraying Max Mayfield in the Netflix science fiction series Stranger Things (2017–present). In 2021, she appeared in the horror film trilogy Fear Street and played the lead role in Taylor Swift's short film All Too Well. Sink has since starred in Darren Aronofsky's psychological drama The Whale (2022), for which she was nominated for the Critics' Choice Movie Award for Best Young Performer.