Margaret Constance "Maisie" Williams (born April 15, 1997) is an English actress. Williams made her acting debut in 2011 as Arya Stark, a lead character in the HBO epic medieval fantasy television series Game of Thrones (2011–2019). She gained recognition and critical praise for her work on the show and received two Emmy Award nominations. Williams' other television appearances include Ashildr in the BBC science fiction series Doctor Who (2015), starring in the British docudrama television film Cyberbully (2015), and in the British science-fiction teen thriller film iBoy (2017). She played the central character in the comedy action drama miniseries Two Weeks to Live (2020) and portrayed punk rock icon Jordan in Pistol (2022), a biopic about the Sex Pistols. Williams also voiced Cammie MacCloud in the American animated web series Gen:Lock (2019–2021).

In 2014, she starred as Lydia in her first feature film, the coming-of-age mystery drama The Falling, for which she received critical acclaim and several awards. She co-starred in films such as the romantic period-drama film Mary Shelley (2017), the animated prehistoric sports comedy film Early Man (2018), and the romantic comedy-drama film Then Came You (2018). In 2018, she made her stage debut in Lauren Gunderson's play I and You at the Hampstead Theatre in London, to positive reviews. In 2020, she starred in the superhero horror film The New Mutants and the psychological thriller The Owners.