Karen Sheila Gillan was born on November 28, 1987, in Inverness, Scotland, to parents Raymond John Gillan and Marie Paterson. She developed an interest in acting at a young age, participating in local theatre productions and attending drama classes. She left Inverness at age 16 to pursue acting studies at Telford College in Edinburgh and later moved to London to attend the Italia Conti Academy of Theatre Arts, which she left midway through the course to focus on her acting career.
Gillan’s early television work included guest appearances in various British series. Her breakthrough role came in 2009 when she was cast as Amy Pond, the companion to the Eleventh Doctor (Matt Smith) in the BBC science fiction series Doctor Who. She remained a series regular until 2012, becoming a popular and recognizable figure in British television.
Following her success in Doctor Who, Gillan transitioned into film roles. She gained international recognition for her portrayal of Nebula in the Marvel Cinematic Universe (MCU), first appearing in Guardians of the Galaxy (2014). She reprised the role in Guardians of the Galaxy Vol. 2 (2017), Avengers: Infinity War (2018), Avengers: Endgame (2019), and Guardians of the Galaxy Vol. 3 (2023). Her performance as Nebula involved extensive makeup and prosthetics work.