Jason Iain Flemyng (born 25 September 1966) is an English actor.

Flemyng is known for his film work, which has included roles in British films such as Lock, Stock and Two Smoking Barrels (1998) and Snatch (2000), both for Guy Ritchie, as well as Hollywood productions such as Rob Roy (1995), the Alan Moore comic book adaptations From Hell (2001) and The League of Extraordinary Gentlemen (2003), and The Curious Case of Benjamin Button (2008). He has also appeared in prominent roles in both theatre and television in the UK. Flemyng speaks French fluently, and has made three films in that language. He won the Best Actor Award at the Geneva Film Festival for his role in 1996's Alive and Kicking.