John Slattery made his debut in the television series ‘Dirty Dozen: The Series’ in 1988. He was next seen in television series and films such as ‘Father Dowling Mysteries’ (1989), ‘Under Cover’ (1991), ‘Under Cover’ (1991), and ‘Before the Storm’ (1991). In 1991, he starred as ‘Al Kahn’ in the American television drama series ‘Homefront’ created by Lynn Marie Latham and Bernard Lechowick. The series aired 42 episodes before going off-air in 1993. He went on to make his big-screen debut in the 1996 American suspense drama film ‘City Hall’ directed by Harold Becker. The film received mixed to positive reviews from critics. That same year, he also appeared in the American action film ‘Eraser’ where he played the role of ‘FBI Agent Corman.’ The film received mixed reviews from critics. He continued to star in films like ‘My Brother's War’ (1997), ‘Red Meat’ (1997), ‘Harvest’ (1998), ‘The Naked Man’ (1998), and ‘Where's Marlowe?’ (1998). The year 2000 saw the release of the American crime drama film ‘Traffic’ where Slattery was seen playing the role of ‘Assistant District Attorney Dan Colier.’ The film saw critical acclaim and received 4 ‘Academy Award’ nominations. It was also a major commercial success and grossed over $207.5 million on a budget of $48 million.Â
He went on to star in films like ‘Sam the Man’ (2001), ‘Bad Company’ (2002), ‘The Station Agent’ (2003), ‘Mona Lisa Smile’ (2003), ‘Dirty Dancing: Havana Nights’ (2004), ‘The Situation’ (2006), and ‘Flags of our Fathers’ (2006). In 2007, he joined the main cast of the American period drama television series ‘Mad Men.’ He played the role of Roger Sterling which earned him 2 ‘Primetime Emmy Award’ nominations. The series ran for 7 seasons and went off-air in 2015. In 2010, he portrayed Howard Stark in the American superhero film ‘Iron Man 2’ directed by Jon Favreau. Even though the film opened to mixed reviews, it performed well at the box office. The following year, he was seen playing the role of ‘Richardson’ in the American science fiction romantic thriller film ‘The Adjustment Bureau’ directed by George Nolfi. The film was a critical and commercial success. He next appeared in films like ‘In Our Nature’ (2012), ‘Bluebird’ (2013), ‘Ted 2’ (2015), ‘Spotlight’ (2015), ‘Captain America: Civil War’ (2016), ‘Churchill’ (2017), and ‘Avengers: Endgame’ (2019). He was last seen in the Episode: "Alf Musik" of the American musical comedy television series ‘Girls5eva’ in 2021.