Sophie Louise Cookson (born 15 May 1990) is an English actress best known for portraying secret agent Roxanne "Roxy" Morton / Lancelot in the 2014 spy film Kingsman: The Secret Service and its 2017 sequel The Golden Circle, and for playing the title role in The Trial of Christine Keeler.
Cookson was brought up in Sussex and later Suffolk where she attended Woodbridge School. She was involved in singing and musical theatre since childhood. After being part of a theatre company that had toured Japan, she decided to quit acting to study art history and Arabic at the University of Edinburgh. However, she soon dropped out to pursue an acting career and attended the Oxford School of Drama for three years, and graduated in 2013.
While still attending Oxford Drama School in her senior year, she was cast as Grace Mohune in the Sky 1 miniseries Moonfleet, based on the J. Meade Falkner novel of the same name. In early 2014, she appeared in the film adaption of the Rosamunde Pilcher novel Unknown Heart produced by German television network ZDF, portraying Millie Lancaster. The same year, she also landed her first big screen role, replacing Emma Watson for the part of secret agent Roxanne "Roxy" Morton / Lancelot in the spy film Kingsman: The Secret Service, based on the comic book The Secret Service by Mark Millar and Dave Gibbons.