Scottish actor Mark Bonnar started acting on stage in the 1990s and made his screen debut in 2001 with an episode of television series ‘Rebus’. This was followed by roles in TV series 'Wire in the Blood' (2002) and ‘Afterlife’ (2005) as well as TV movie ‘Loving You’ (2003). In 2005, he began appearing in the role of Bruno Jenkins in BBC One’s medical drama series ‘Casualty’ and continued with it till 2006. In 2007, he was seen in the role of Ray Moore in ITV's police procedural series ‘The Bill’ (8 episodes) and thereafter, in 2009, played the part of D.S. Ben Holt in the BBC's science fiction police drama miniseries 'Paradox'. During this period, he also acted in the TV movie 'The Trial of Tony Blair' (2007), the two-part TV drama 'Britz' (2007) as well as an episode each of TV miniseries documentary 'Spies, Lies and the Superbomb' (2007) and TV series ‘The Inspector Lynley Mysteries’ (2007) and ‘PhoneShop’ (2010). Additionally, he acted in a couple of episodes each of TV series ‘Taggart’ (2003, 2010) and ‘Doctor Who’ (2011) and appeared as himself in the 2 episodes of TV series documentary ‘Doctor Who Confidential’ (2011) too.
After this, Mark Bonnar was roped in to play the role of Detective Finney in the psychological horror thriller black comedy mystery series ‘Psychoville’ (2011, 6 episodes). A couple of years later, in 2013, he became a part of the BBC Scotland crime drama series ‘Shetland’. Based on the novels of the Ann Cleeves (British mystery and crime writer), the series has him in the role of Duncan Hunter. He has appeared in all the seven series of the show till 2022 (30 episodes). In 2014, he landed yet another significant role of his career – that of the corrupt police officer DCC Michael Dryden in the second season of BBC’s police procedural series ‘Line of Duty’ (6 episodes). The series received critical acclaim and won him his first nomination at the 'BAFTA Awards Scotland' (for Best Actor in Television). Mark Bonnar won his second nomination at the 'BAFTA Awards Scotland', in the same category, for his portrayal of the character of Chris in Channel 4’s comedy series ‘Catastrophe’. The series aired its first two seasons in 2015 following which the third and fourth seasons were telecasted in 2017 and 2019 respectively. During this time, he was seen in television miniseries ‘Jekyll & Hyde’ (2015) and ‘Undercover’ (2016) as well as television series ‘New Blood’ (2016) too. In the first, he played the role of Lord Protheroe while in the second one, he portrayed the part of John Halliday. In the last of these, he played the role of Peter Mayhew, the government health advisor. In addition, he played the role of Officer Meekie in both the TV movie (2016) and sitcom (2017) ‘Porridge’.
In 2017, he played the role of the criminal barrister Colin Osborne in the second season of ITV crime drama series ‘Unforgotten’. The series received critical acclaim and bagged Mark Bonnar his first ‘BAFTA Scotland Award’ for Best Actor – Television. The same year, he was also seen in the roles of Gary Carmichael in the four-part psychological thriller miniseries ‘Apple Tree Yard’, and Eric Morecambe in the drama TV film ‘Eric, Ernie and Me’. For his work in ‘Unforgotten’, ‘Eric, Ernie and Me’, ‘Catastrophe’ and ‘Apple Tree Yard’, he received the ‘Broadcasting Press Guild Award’ for Best Actor. The next year, he was seen in the third season of Channel 4’s critically acclaimed science fiction television series ‘Humans’. In it, he played the role of Neil Sommer, a charming scientist on a government commission.
From 2019 to 2021, Mark Bonnar played the leading role of Max in two seasons of the critically acclaimed and successful thriller mystery series 'Guilt'. The show bagged him yet another nomination at the ‘BAFTA Scotland Award’ for Best Actor – Television. In 2019 again, he played the role of Field in BBC's six-episode Cold War miniseries 'Summer of Rockets', and Miles in three episodes of another television series titled ‘Defending the Guilty’. In 2020, he played the character of Paul Smith in three-episode drama series ‘Quiz’. All three shows, once again, received positive reviews from critics. Other television projects in which he acted since 2012 include TV series ‘Playhouse Presents’ (2012), ‘Twenty Twelve’ (2012), ‘The Paradise’ (2012), ‘Silent Witness’ (2013), ‘Case Histories’ (2013), ‘The Great Scott’ (2013), ‘Law & Order: UK’ (2014), ‘Grantchester’ (2014), ‘Midsomer Murders’ (2015), ‘Vera’ (2015), ‘Home Fires’ (2015) and ‘Urban Myths’ (2018).
In his career, Mark Bonnar has acted in several films too. These include ‘X Moor’ (2014), ‘Camera Trap’ (2014), ‘All the Ordinary Angels’ (2015), ‘Sunset Song’ (2015), ‘Billionaire Ransom’ (2016), ‘Say My Name’ (2018), ‘The Kid Who Would Be King’ (2019) and ‘Operation Mincemeat’ (2021). The last of these was a war drama film which had him in the role of Jock Horsfall. The movie received favourable reviews from critics and earned him yet another nomination at the ‘BAFTA Scotland Award’ (Best Actor – Film).
Mark Bonnar has also lent his voice in several projects. These include the 2020 short animated TV movie ‘Zog and the Flying Doctors’ (role: Unicorn) and the 2021 animated TV series ‘The Brilliant World of Tom Gates’ (role: Mr. Fullerman). He has narrated the TV series documentary called ‘Dispatches’ (2008), the documentary short ‘Amazing Mighty Micro Monsters’ (2015), the documentary ‘Wild Flight: Conquest of the Skies 3D’ (2016) and the TV miniseries documentary ‘The Forest’ (2018) too. In 2017-2018, he appeared as a himself/storyteller in the TV series short ‘CBeebies Bedtime Story’, and read bedtime stories in various episodes. In addition, he has lent his voice in several video games as well like ‘Assassin's Creed IV: Black Flag’ (2013, role: Edward Blackbeard Thatch), ‘Sword Coast Legends’ (2015, role: Izhkin), ‘Battlefield 1’ (2016, role: Townsend) and ‘Assassin's Creed Valhalla’ (2020, role: King Ceolwulf/Cynon).