James Garner is one of my favorite actors, and the star of one of my favorite shows ("The Rockford Files"). He's an effortless performer, a guy who looks incredibly natural on screen and always turns in a good performance. Of course, he's best known for his TV work, but his film work is always good too.
Maybe his success comes from the fact that he and his characters seem so relatable. Garner's men, whether they're Maverick or Rockford, are real people. He's not a he-man action star, but he's like a lot of us (or like a lot of us wish we'd be) - friendly, not the strongest or best looking guy but usually ready with a quip.
I'd recommend (to any Garner fans who haven't seen it) "Twilight." In it, he plays an ex-cop/PI who's involved in a case Paul Newman's character is investigating. Not only is it a great piece for James Garner, but it's a very well-made modern day "film noir" and mystery.