Vanessa Nuala Kirby (born April 18, 1988) is an English actress. She rose to international prominence with her portrayal of Princess Margaret in the Netflix drama series The Crown (2016–2017), for which she won the BAFTA for Best Supporting Actress. For her performance in the film Pieces of a Woman (2020), she won the Volpi Cup for Best Actress. She received a nomination for the Academy Award for Best Actress.

Kirby made her professional acting debut on stage, with acclaimed performances in the plays All My Sons (2010), A Midsummer Night's Dream (2010), Women Beware Women (2011), Three Sisters (2012), and as Stella Kowalski in A Streetcar Named Desire (2014). She also appeared in the action films Mission: Impossible – Fallout (2018), Hobbs & Shaw (2019), and The Fantastic Four: First Steps (2025), and portrayed Empress Joséphine in the historical drama Napoleon (2023).