Jason Iain Flemyng (born 25 September 1966 in Putney, London) is an English character actor of Scottish descent.
His first prominent movie role was in Lock, Stock & Two Smoking Barrels. He seems to particularly excel at supporting roles and played a number of them in his prolific career, alternating between movies and television productions.
He was in a relationship with Lena Headey for nine years.
- The Jungle Book (1994) as Lieutenant John Wilkins
- Rob Roy (1995) as Gregor
- Spice World (1997) as Brad
- The Red Violin (1998) as Frederick Pope
- Deep Rising (1998) as Mulligan
- Lock, Stock & Two Smoking Barrels (1998) as Tom
- Alice in Wonderland (1999) as the Knave of Hearts
- Snatch. (2000) as Darren
- From Hell (2001) as Netley
- The Bunker (2001) as Cpl. Baumann
- The League of Extraordinary Gentlemen (2003) as Dr. Henry Jekyll / Edward Hyde
- Layer Cake (2004) as Crazy Larry
- Seed of Chucky (2004) as Santa
- Transporter 2 (2005) as Dimitri
- Stardust (2007) as Primus
- The Curious Case of Benjamin Button (2008) as Thomas Button
- Solomon Kane (2009) as Malachi
- Clash of the Titans (2010) as Acrisius
- Kick-Ass (2010) as Lobby Goon
- The Social Network (2010) as the Spectator
- Ironclad (2011) as Beckett
- Hanna (2011) as Sebastian
- X-Men: First Class (2011) as Azazel
- Great Expectations (2012) as Joe Gargery
- Welcome to the Punch (2013) as Harvey Crown
- Viy (2014) as Jonathan Green
- Viy 2: Journey to China (2019)
- Stonehearst Asylum (2014) as Swanwick
- The Young Indiana Jones Chronicles (1992) as Emile
- Marple (2004) as Lawrence Redding
- Primeval (2009-2011) as Danny Quinn
- Black Mirror Series Two (2013) as Jack Napier
- The Musketeers (2014) as Vadim
- The Missing (2014) as Mark
- The Last Kingdom (2015) as King Edmund
- SS-GB (2017) as Colonel George Mayhew
- Pennyworth (2019-2021) as Lord James Harwood
- Fake American: In The Curious Case of Benjamin Button he plays the titular character's father, a New Orleans native.
- Production Posse: He was frequently cast by Guy Ritchie and Matthew Vaughn.
- Real Life Writes the Plot: Primeval got cancelled and he had pending film commitments when it was Un-Cancelled, resulting in Danny staying in prehistoric times until the fourth season finale.