Jackson was born in Luton, Bedfordshire, the second of four sons to Evelyn and Dennis Jackson.
Neil was introduced to acting when studying drama at GCSE level in Harlington Upper School. His teacher, Nigel Williams, placed him in several of the school plays including Annie, Little Shop of Horrors, Hard Times, and West Side Story. He also acted in National Youth Theatre as a teenager before moving to Cardiff to study sport at the University of Wales Institute Cardiff (UWIC) in Wales.
In Wales, Jackson started competitive boxing after learning of the British Universities Boxing Championships, an inter-university competition held throughout the whole of Britain. He entered and won the gold at light-middle weight. He went on to successfully defend his title two years later at middle weight. His boxing earned him a scholarship to stay on at UWIC and study for his Master's degree. He graduated in 1998.
Not knowing how to get into acting, Jackson wrote a musical and entered it into a national competition for new writers. It came in third and gained attention from producers in London including Michael Armstrong. He later enrolled in Michael Armstrong's Acting Academy, graduating in 2002.
Jackson's first professional acting job was a UK national touring production of Strindberg's classic Miss Julie. He understudied the lead character, Jean, a role he took over in the West End production later that year. His big break came when Oliver Stone cast him as Perdiccas in Alexander alongside Colin Farrell and Angelina Jolie. He recalls having a black eye and three stitches in his eyebrow when he first met Oliver Stone, a fact he jokes must have assisted him as Stone cast him for the role on the spot. He was also in the football drama Dream Team for a season as lottery winning chairman Phil Wallis.
In 2006 he made a guest appearance on Cold Case, in the episode "Sandhogs" of Season 4. He portrayed "Donny", the victim that was killed in a cave-in by his brother-in-law. Then in 2007 saw the release of The Passage, a film written by Jackson and shot in Morocco, in which he played a lead character alongside Stephen Dorff. The film won the 2008 Jury Award at the Durango Film Festival. He made a guest appearance on CSI: Crime Scene Investigation, in the episode "A La cart" of season 8. He appeared as Ian on How I Met Your Mother. The following year in 2008 he made a guest appearance on CSI: Miami and in 2009 he appeared as a wraith in Stargate: Atlantis.
Jackson shot a scene in Panama for the Bond film Quantum of Solace, where he plays the character of Mr. Slate. He previously starred in the ABC Family original series, Make It or Break It as Sasha Belov. Additionally, Jackson has appeared as Lucas Hellinger, a Blackout conspirator, on the show FlashForward. In 2010 he starred as the chauffeur Harry Spargo in the BBC revival of Upstairs, Downstairs. Jackson was recently cast in the lead role of Sir Percy Blakeney/The Scarlet Pimpernel in Fairbanks Productions' adaptation of the classic tale, scheduled for 2012.
|2005||Breakfast on Pluto||Man at Disco|
|2006||The Last Drop||Flt. Sgt. Simkins|
|2006||The Thirst||Duke of Earl|
|2008||15-40||Kai Hansen||Short film|
|2008||Quantum of Solace||Mr. Slate|
|2009||Table for Three||Tre|
|2010||You Will Meet a Tall Dark Stranger||Alan|
|2014||House of Secrets||Sam||Television movie|
|2001–2003||Dream Team||Phil Wallis||2 episodes|
|2002||Heartbeat||Jeremy Purves||Episode: "The Leopard's Parts"|
|2002||The House That Jack Built||Charlie||Episode: "Dynasty"|
|2002||Is Harry on the Boat?||Matthew||Episode: "#1.10"|
|2002||Ultimate Force||Luke||Episode: "Natural Selection"|
|2002||Silent Witness||Marcus Saul||2 episodes|
|2003||The Last Detective||Stuart Gilley||Episode: "Lofty"|
|2004||Red Cap||Pte. Robbie McCoy||Episode: "Fighting Fit"|
|2005||Sugar Rush||Dale||7 episodes|
|2005||Stargate SG-1||Khalek||Episode: "Prototype"|
|2006||Blade: The Series||Marcus Van Sciver||12 episodes|
|2006||Cold Case||John Donovan||Episode: "Sandhogs"|
|2007||CSI: Crime Scene Investigation||Michael, the waiter||Episode: "A La Cart"|
|2007||How I Met Your Mother||Ian||Episode: "Third Wheel"|
|2008||CSI: Miami||Paul Sanders||Episode: "Won't Get Fueled Again"|
|2008||The Cleaner||Duncan Collins||2 episodes|
|2008||Stargate Atlantis||Wraith||Episode: "Vegas"|
|2009–2010||Make It or Break It||Sasha Beloff||36 episodes|
|2010–2012||Upstairs, Downstairs||Harry Spargo||9 episodes|
|2010||FlashForward||Lucas Hallinger||5 episodes|
|2011||White Collar||David Lawrence||Episode: "On Guard"|
|2013–2015||Sleepy Hollow||Abraham Van Brunt||10 episodes|
|2013||Lightfields||Dwight Lawson||5 episodes|
|2014||Person of Interest||Rick Dillinger||Episode: "RAM"|
|2017||The Originals||Alistair Duquesne||Episode: "Gather Up the Killers"|
- Jackson is patron of UK spinal injuries charity Trust PA, in memory of a friend.
- He's been in the 2004 film Alexander with Joseph Morgan, resulting into these two becoming friends.