Jack O'Connell (born 1 August 1990) is an English actor. Known for his roles as dark, volatile and menacing characters, he has received various accolades, including a British Academy Film Award, an Actor Award and a Gotham Award. He first gained recognition for playing James Cook in the British television series Skins (2009–2010, 2013). He is also known for his roles in the coming-of-age film This Is England (2006), the horror-thriller Eden Lake (2008), the television dramas Dive (2010) and United (2011), and the Netflix Wild West miniseries Godless (2017), for which he received a Critics' Choice Television Award nomination.

O'Connell gave critically acclaimed performances in the independent films Starred Up (2013) and '71 (2014), garnering nominations for the British Independent Film Awards. He subsequently starred as war hero Louis Zamperini in the war film Unbroken (2014), and received the BAFTA Rising Star Award. He has since starred in the thriller Money Monster (2016), the biographical drama Trial by Fire (2018), the BBC miniseries The North Water (2021), the BBC series SAS: Rogue Heroes (2022–present), the Amy Winehouse biographical film Back to Black (2024), the horror film Sinners (2025), and as Jimmy Crystal in the post-apocalyptic horror films 28 Years Later (2025) and 28 Years Later: The Bone Temple (2026).

O'Connell was born on 1 August 1990 into a working-class family in Alvaston, Derbyshire, England. His father, Johnny Patrick O'Connell, was an Irish citizen from Ballyheigue, Ireland, who worked on the British railways for the Bombardier Transportation Company until his death from pancreatic cancer in 2009. His mother, Alison (née Gutteridge), who is English, was employed by the British Midland airline before taking on management of her son's career. His younger sister, Megan, is an actress. As the grandson of Ken Gutteridge, a player and later manager at Burton Albion FC, O'Connell aspired to become a professional footballer. He played as a striker for Alvaston Rangers and was later scouted by Derby County FC, where he had trials. After a series of injuries ended his career, he wanted to join the British Army, believing it to be his only realistic option to make an honest living. His parents sent him to the Army Cadet Force when he was 12 with the aim of teaching him discipline, but his juvenile criminal record prevented him from enlisting in the army.

As a youth, O'Connell was in and out of court on charges related to alcohol and violence, and he received a one-year young offender's referral order when he was 17. Regarding his past transgressions, he has described himself as 'a product of [his] environment'. At age 16, O'Connell left Saint Benedict Catholic School with two GCSEs in drama and English. He later reflected on his 'brutal' experience at Saint Benedict: 'What I learnt aside from anything academic at school was probably very valuable lessons in terms of how to lie, how to play the game, how to play authority against itself.' He took an interest in acting during the compulsory drama classes, and from age 13 he attended the free Television Workshop in Nottingham, where he trained in drama twice a week. He began attending auditions in London, where he sometimes slept outside because he was unable to afford a hotel. He eventually moved to Hounslow in London, working in between acting parts as a farmhand in Cobham, Surrey.

Since the start of his career, O'Connell has mainly played young delinquents; The New York Times writer John Freeman noted retrospectively, 'If a British film called for a tough case, a grappler, someone with a bit of grit, chances were O'Connell got the part. [He] has delivered one gripping physical performance after another, bringing an electric authenticity to the portrayal of angry, troubled youth.' O'Connell made his professional acting debut in 2005 when he played a runaway with anger issues in an episode of Doctors, followed by a recurring role as a boy accused of rape in The Bill. His stage debut came that same year after a rendition of the play The Spider Men by the Television Workshop was selected to be performed at the Royal National Theatre in London. O'Connell played his debut film role in This Is England (2006), a critically acclaimed coming-of-age drama set in the skinhead subculture of the early 1980s. At age 15, he was deemed too old to play the main character, leading filmmaker Shane Meadows to write the supporting role of the belligerent Pukey specifically for him.

During 2007, O'Connell appeared in television episodes of Waterloo Road, Holby City and Wire in the Blood. He played a 15-year-old pupil involved in a sexual relationship with his teacher in the play Scarborough, first performed at the Edinburgh Festival before its transfer the following year to London's Royal Court Theatre. Variety's David Benedict wrote of his stage performance, 'His sincere grasp of Daz's innocent tenderness is, paradoxically, a sign of the character's—and the actor's—unexpected maturity.' In the horror–thriller Eden Lake (2008), which received positive reviews, O'Connell played a psychopathic gang leader who terrorises a young couple. He next starred as a juvenile delinquent in 'Between You and Me' (2008), an educational film produced by the Derbyshire Constabulary, followed by a minor role in the ITV serial Wuthering Heights (2009).

O'Connell first found fame, chiefly among people his age, as the troubled and hard-living James Cook in the third and fourth series of the E4 teen drama Skins (2009–10). Grantland writer Amos Barshad opined that among his co-stars, which included Dev Patel and Nicholas Hoult, none 'ever quite matched the luminescent, leering mania of O'Connell's Cook. As a preposterously ramped up bad boy, Cook was almost like a baby Tyler Durden.' He won a TV Choice Award for Best Actor for his performance in the fourth series. O'Connell later reprised his role in the feature-length special Skins Rise (2013), which follows a twenty-something Cook on the run from authorities. He has said of Cook, 'He's probably the most similar character to myself that I had the good fortune of portraying', though he noted that, unlike Cook, he had matured beyond adolescence.

In the vigilante thriller Harry Brown (2009), which polarised critics, O'Connell played an abused child turned vicious gang member. He impressed lead actor Michael Caine, who shouted "Star of the future!" at him during filming. His portrayal of a teenaged father in the BBC Two drama Dive (2010) earned him critical praise; Euan Ferguson of The Guardian described it as 'a performance that is of an actor twice his years: mesmerising, comedic and soulful.' The Daily Telegraph critic Olly Grant concurred, writing, 'He was a revelation; nuanced, understated, wise beyond his years.' Following a lead role in the Sky1 serial The Runaway (2011), set in the criminal underworld of 1970s London, O'Connell starred as football player Bobby Charlton in another well-received BBC Two drama, United (2011), which chronicles the 1958 Munich air crash that killed eight players of Manchester United.