His film credits include Emma (1996), An Ideal Husband (1999), Amistad (1997), The Winslow Boy (1999), Gosford Park (2001) and Enigma (2001).

[4] Northam made his screen debut on television in the series American Playhouse, as Mr. Benson in the episode "Suspicion".

[3] He has appeared frequently in British films such as Carrington (1995),[3] Emma (1996),[3] The Winslow Boy (1999),[3] An Ideal Husband (1999),[3] Enigma (2001),[3] and as Welsh actor and singer Ivor Novello in Gosford Park (2001).

[7] His audiobook work includes The Silver Chair (The Chronicles of Narnia, Book 6) by C. S. Lewis,[8] The Real Thing and Other Short Stories and The Aspern Papers, both written by Henry James.

[8] In the Gosford Park soundtrack, Northam sings the Ivor Novello songs "And Her Mother Came Too",[9] "What a Duke Should Be",[9] "Why Isn't It You",[9] "I Can Give You the Starlight",[9] and "The Land of Might Have Been",[9] accompanied by his brother Christopher on piano.