Keira Christina Knightley (/ˈkɪərə ˈnaɪtli/ KEER-ə NYTE-lee; born 26 March 1985) is an English actress. Known for her work in independent films and blockbusters, particularly period dramas, she has received numerous accolades, including nominations for two Academy Awards, two British Academy Film Awards, four Golden Globes, and a Laurence Olivier Award. Films in which she has appeared have grossed over $6.4 billion worldwide. In 2018, she was appointed an OBE at Buckingham Palace for services to drama and charity.

Born in London to actor Will Knightley and playwright Sharman Macdonald, Knightley obtained an agent at age six and initially worked in commercials and television films. Following a minor role as Sabé in Star Wars: Episode I – The Phantom Menace (1999), her breakthrough came when she played a tomboy footballer in Bend It Like Beckham (2002) and co-starred in Love Actually (2003). She achieved global recognition for playing Elizabeth Swann in the Pirates of the Caribbean film series (2003–2007; 2017).

For her portrayal of Elizabeth Bennet in Pride & Prejudice (2005), Knightley was nominated for the Academy Award for Best Actress. She starred in several more period films over the next few years, including Atonement (2007), The Duchess (2008), A Dangerous Method (2011), and Anna Karenina (2012). She took on contemporary-set parts in Begin Again (2013) and Jack Ryan: Shadow Recruit (2014), and returned to historical films playing Joan Clarke in The Imitation Game (2014), earning a nomination for the Academy Award for Best Supporting Actress. She has since starred as the title character in Colette (2018), journalist Loretta McLaughlin in Boston Strangler (2023), and a spy in the thriller series Black Doves (2024). On stage, Knightley has appeared in two West End productions: The Misanthrope in 2009, which earned her an Olivier Award nomination, and The Children's Hour in 2011. She also starred as the titular heroine in the 2015 Broadway production of Thérèse Raquin.

Knightley is known for her outspoken stance on social issues and has worked extensively with Amnesty International, Oxfam, and Comic Relief. She is married to musician James Righton, with whom she has two daughters.

Keira Christina Knightley was born on 26 March 1985 in the southwestern London suburb of Teddington, to stage actor Will Knightley and playwright Sharman Macdonald. She was born at home in her kitchen with no medical assistance save a midwife. She was meant to be named "Kiera", the anglicised form of "Kira", after the Soviet figure skater Kira Ivanova, whom her father admired; however, Macdonald, who is dyslexic, misspelt the name when she registered her daughter's birth certificate, writing the e before the i. Her father is English and her mother is of Scottish and Welsh descent. Knightley has an older brother, Caleb. Macdonald worked as a playwright after her acting career came to an end. Knightley's parents encountered substantial financial difficulties following the birth of her brother; her father, a "middling" actor, agreed to a second child only if her mother sold a script first. However, her parents' varying degrees of success did not deter Knightley's curiosity about the profession. Macdonald introduced her children to theatre and ballet very early, inspiring Knightley's interest in acting.

Knightley attended Teddington School. She was diagnosed with dyslexia at six, but by the time she was eleven, with her parents' support, she says, "they deemed me to have got over it sufficiently". She is still a slow reader and cannot read out loud. Due to her hard time reading, the school classified her as having "special educational needs," which made her feel discouraged. Her parents used the promise of acting to encourage her to work harder. Knightley has said she was "single-minded about acting". At age three, she requested to obtain an agent like her parents and secured one at six. This led to her taking a number of small parts in television dramas. She acted in a number of local amateur productions, which included After Juliet, written by her mother, and United States, written by her drama teacher. Knightley began studying her A-Levels at Esher College in Surrey but left after a year to pursue an acting career. Her mother's friends encouraged her to go to drama school, which she declined for financial and professional reasons.

After obtaining an agent at age six, Knightley began working in commercials and small television roles. Her first onscreen appearance was in the 1993 Screen One television episode titled "Royal Celebration". She then played Natasha Jordan, a young girl whose mother is involved in an extramarital affair, in the romantic drama A Village Affair (1995). After appearing in a spate of television films through the mid-to-late 1990s, including Innocent Lies (1995), The Treasure Seekers (1996), Coming Home (1998), and Oliver Twist (1999), Knightley landed the role of Sabé, Padmé Amidala's handmaiden and decoy, in the 1999 science fiction blockbuster Star Wars: Episode I – The Phantom Menace. Her dialogue was dubbed over by Natalie Portman, who played Padmé. Knightley was cast in the role because of her close resemblance to Portman; even the two actresses' mothers had difficulty telling their daughters apart when they were in full make-up.

In her first major role, the 2001 Walt Disney Productions television film Princess of Thieves, Knightley played the daughter of Robin Hood. In preparation for the part, she trained for several weeks in archery, fencing, and riding. Concurrently, she appeared in The Hole, a thriller that received a direct-to-video release in the US. The film's director Nick Hamm described her as "a young version of Julie Christie". Knightley also took on the role of Lara Antipova in the 2002 miniseries adaptation of Doctor Zhivago, to positive reviews and high ratings. In the same year, Knightley starred as a pregnant drug addict in Gillies MacKinnon's drama film Pure. Co-starring Molly Parker and Harry Eden, the film had its world premiere at the 2002 Toronto International Film Festival. In a retrospect review for AboutFilm.com, Carlo Cavagna noted Knightley's screen presence and wrote that "[although Knightley] doesn't have half of Parker's ability [...] she has spunk and grit [and] shines brightly in Pure".