Powers Boothe is able to play a mixture of charm, menace, introspection and brutality in a wide variety of roles. Still, he's largely unappreciated, despite appearing in some of the best and most critically acclaimed films and TV shows in recent memory.
He steadily appears on film, but I think his meatiest parts have been on TV. I'm biased (I'm the editor of the show and I love it) but people curious about Mr. Boothe should check out "Philip Marlowe, Private Eye." Not only is it a terrific series in its own right, but it's a star turn for Mr. Boothe, who takes the role of the iconic detective and makes it his own (not easy when Humphrey Bogart has also played the character!)
More recently, he was the only good part of the awful sixth season of "24." And he was consistently strong on "Deadwood," the lamentably short-lived HBO drama. Whatever he's in, regardless of the quality of the piece itself, it's a sure-thing Powers Boothe is going to turn in a great performance.