He launched his career in Australia. He got his actors' union card at the age of 9 (in 1986) and at the age of 11 he started working in ads. His first onscreen acting performance was in the 1994 Australian TV-movie Baby Bath Massacre as Adrian. Between acting jobs, Stapleton did several types of work: modeling, cleaning animal cages in a pet shop, working as a grip (taking care of the camera equipment) in a considerable number of films and TV productions (The Elephant Princess, Rush, Tangle) in front and behind the camera, working on building sites, and assisting carpenters.
Before landing a role as Josh Hughes in Australian soap opera Neighbours in 1998, he appeared in a string of little-seen features and homegrown dramas. Other notable roles include Justin Davies in the Australian televised serial The Secret Life Of Us (between 2003 and 2005), Fearless in the motion picture December Boys (released in 2007), special agent Wilkins in the mainstream feature, The Condemned (an American action film distributed in 2007). But it was with Stapleton's performance in the Academy Award nominated film Animal Kingdom, which premiered at the 2010 Sundance Film Festival, that he made an international breakthrough.
When Animal Kingdom won the Grand Jury Prize at the Sundance Film Festival interest in him sparked on two continents and his career has taken him across the globe. He made his second appearance in the Underbelly, an Australian true crime drama television series. This time he was the lead character, Colin McLaren in Underbelly Files: Infiltration, an endurance test and the first challenging shoot of his career. Previously he played Pat Barbaro in Underbelly (episode Suffer the Children) in 2008.
Stapleton played the lead role, Greek leader Themistocles, in the film 300: Rise of an Empire (2014). He was honoured on 24 October 2013 with a Breakthrough Award at an exclusive Australians in Film Benefit Dinner held in Los Angeles.
In early 2014, Stapleton was in Thailand for the filming of the TV series Strike Back. In February on a night out in Bangkok after work, he fell off a tuk-tuk (a type of motorised rickshaw) and suffered a head injury that left him in a coma. Shooting for the show was paused for six months to allow his full recovery. Airing of the final season was also pushed to 2015.
