Sidse Babett Knudsen is a Danish actress of theater, television, and film. Knudsen made her screen debut in the 1997 improvisational comedy Let's Get Lost, for which she received the Robert Award and the Bodil Award for Best Actress.

After the critical success of her debut, Knudsen came to be regarded as one of the best Danish actresses of her generation. In 2000, she again received both awards for Best Actress for the romantic comedy-drama The One and Only. In 2016, she received the César Award for Best Supporting Actress for the film L'Hermine. Knudsen was also nominated for awards for her roles in the films Monas Verden and After the Wedding.

Knudsen gained international recognition for her leading role as the fictional Prime Minister of Denmark Birgitte Nyborg in the Danish television series Borgen.