In Harry Potter, Jason plays Lucius Malfoy, the Death Eater father of Harry's nemesis, Draco Malfoy. Jason will continue to play Malfoy in the Harry Potter films that will follow The Chamber of Secrets...at least until The Order of the Phoenix, after which Malfoy in placed in Azkaban and may or may not continue to be a regular chracter.
In the Patriot Jason portrays Colonel William Tavington, a dragoon fighting for the British Army in the American Revolution. Yes once again Jason plays the villian(but he does it so well!) Tavington is a ruthless fighter, and the nemesis of Mel Gibson's character Benjaimin Martin...probably because Tavington kills two of Martin's sons which is bound to get any man a little angry.