8. Thomas Kretschmann
Another German actor who has achieved a reasonable degree of success in Hollywood cinema is Thomas Kretschmann, whose filmography includes parts in King Kong, Blade II, Valkyrie and the upcoming Avengers: Age Of Ultron. He has maintained a steady presence on the European side of the pond as well, appearing in the likes of The Pianist and the aforementioned Der Untergang (Downfall). His appearance in 24 was a fairly low-key one, as the German played a mysterious arms dealer named Max, who appeared on screen for just a handful of minutes in the final two episodes of the second season, where he is part of a conspiracy (alongside Peter Kingsley and another character named Alexander Trepkos) to initiate American military intervention in the Middle East, which he can profit from, The character reappears as the principal villain of 24: The Game, an underrated PS2 title that bridged the gap between seasons two and three (despite being released a few years afterwards).
7. John Hawkes
Despite him being an Oscar nominee with a handful of appearances in other critically lauded films, you'd be hard pressed to find many individuals that could immediately recognise John Hawkes if he sat next to them on the bus. Such relative anonymity is perhaps what has allowed Hawkes to thrive in the likes of Winter's Bone (which secured him his Oscar nomination, and brought Jennifer Lawrence to the attention of the world for the first time), The Sessions (for which he should've gotten a second nomination for his portrayal of a paralysed poet attempting to lose his virginity), Lincoln and Martha Marcy May Marlene (which brought Elizabeth Olsen to the attention of the world for the first time I'm seeing a trend here...). The 54 year-old has also racked up a sizable television resume over the years, though most of his appearances have been in singular episodes of series. He was a regular on the lauded Deadwood, however, and managed three episodes of Lost and two episodes of 24, appearing in the first season as a mercenary named Greg Penticoff.