Karl David Sebastian Dencik (born 31 October 1974) is a Swedish-Danish actor. He has acted in both Swedish and Danish films, and has also had major roles in English-language films and series including Tinker Tailor Soldier Spy (2011), The Girl with the Dragon Tattoo (2011), Top of the Lake (2017), McMafia (2018), Chernobyl (2019), and the James Bond film No Time to Die (2021).

Dencik is a two-time Robert Award winner, for Best Actor in a Leading Role for A Soap (2006) and Robert Award for Best Actor in a Supporting Television Role for The Chestnut Man (2021). He won a Guldbagge Award for Best Supporting Actor for The Perfect Patient (2019). He is also a seven-time Bodil Award nominee.