Karen Sheila Gillan (/ˈɡɪlən/; born 28 November 1987) is a Scottish actress and filmmaker. She gained recognition for her work in British film and television, particularly for portraying Amy Pond, a primary companion to the Eleventh Doctor in the science fiction series Doctor Who (2010–2013). Her early film roles include the thriller Outcast (2010) and the romantic comedy Not Another Happy Ending (2013). She worked on the British stage, appearing in John Osborne's play Inadmissible Evidence (2011).

Gillan made her Hollywood debut in 2013, starring in the horror film Oculus, then played the lead in the ABC rom-com sitcom Selfie (2014). She achieved stardom for portraying Nebula in several films of the Marvel Cinematic Universe (2014–2023), which are among the highest-grossing films of all time, and Ruby Roundhouse in the fantasy films Jumanji: Welcome to the Jungle (2017), Jumanji: The Next Level (2019), and Jumanji: Open World (2026). She also wrote and directed the drama film The Party's Just Beginning (2018), which she also starred in.