Katheryn Winnick (born December 17, 1977) is a Canadian actress. She is known for her starring roles in the television series Vikings (2013–2020), Wu Assassins (2019), and Big Sky (2020–2023), and her recurring role on the television series Bones (2010–2011). She also starred in the films Amusement (2008), Choose (2010), A Glimpse Inside the Mind of Charles Swan III (2012), The Art of the Steal (2013), Polar (2019), and The Marksman (2021).

Early life
Winnick was born in Etobicoke, Ontario, and is of Ukrainian descent. She spoke Ukrainian as her first language and did not begin speaking English until she was eight years old. She began training in martial arts at age seven, and obtained her first black belt at 13. By age 21, she had started three Taekwondo schools. She taught Taekwondo and self-defense to actors while completing her degree in kinesiology at York University, Toronto. Winnick studied at and is an alumna of the William Esper Studio.

Winnick started acting as a young girl at her community center in Toronto. She had directed plays in her high school and won a scholarship for drama and directing while attending Richview Collegiate Institute.