Is there an actor who incites more controversy than Sean Penn? The screen star, who has a small but decisive role in Terrence Malick's Tree of Life, gets mixed reviews from critics Glenn Whipp and Glenn Kenny.
I've always admired the singularly challenging actor/writer/director determined to swim against the Hollywood mainstream, even if I don't always like his confrontational characters and attitude. 
As his soul-roiling agitation sets him apart from other actors of his generation (he burst on screen 30 years ago in Taps,  a thoughtful contrast both to the muscular authoritarian Tom Cruise and the idealistic Tim Hutton), so it distinguishes his work as a filmmaker.
"If you need to be entertained and comfortable," Penn hectored me a decade ago during an interview, "then my movies are not for you."  He was referring to his directorial effort The Pledge, a riveting character study starring Jack Nicholson as a retired detective using a loved one to bait a serial killer.
Very much liked Penn's The Pledge and Into the Wild, which he also directed, which, like his best performances (Dead Man Walking, Mystic River, Milk) grapple with moral decisions rather than illustrating them. Both as an actor or a director, Penn's movies have the pugilistic intensity of a guy boxing his demons.
He's delivered great performances in movies few people saw: At Close Range, as the son who betrays his father to the police; Shanghai Surprise, as a jaunty tie salesman, Racing With the Moon as the high-schooler who enlists in the Marines. Penn is riveting because he uses those pale eyes the color of winter sky to reveal a man as transparent as water and turbulent as a riptide.
He is personally funny in a self-deprecating way and can be hilarious on screen. Yet his filmography includes just a handful of comedies. Memorably he was the "hey dude, let's party" stoner in Fast Times at Ridgemont High, the jazz guitarist in Woody Allen's Sweet and Lowdown and drolly funny as Harvey Milk in Milk, perhaps the first Penn performance where he deployed his considerable charisma. When I asked him about why there were so few comedies on his resume, he deadpanned that most of the scripts he reads are bad and that "bad serious is less bad than bad funny."
The only two Penn performances I won't defend are The Interpreter (an apparent paycheck movie) and I am Sam (a naked Oscar bid), both unworthy of him.
Your thoughts? Favorite Penn performance?