Brad Pitt has starred in dozen of major Hollywood movies, and while he has somewhat of a reputation as a ladies' favorite, it would definitely be off base to call him a pretty boy. Many characters played by Pitt are amazingly tough, with some being scarily so or psychopathic to boot. Before judging the actor's work as being "pretty boy" or somewhere run of the middle, you will definitely want to consider some of these movies he's been in before writing him off as a guy who can play a really dangerous character well.
In "Fight Club," Brad plays the role of Tyler Durden, a brilliant psychopath who is actually the alter-ego to Ed Norton's more button down self. Strong, smart, and very much the sociopath, this character should put to rest any accusations of Pitt as a pretty boy only.
The movie "Snatch" came out the next year, and in this film Brad Pitt very convincingly plays the part of a gypsy bare knuckle boxing champion, Mickey O'Neil. The only way to describe this character is an iron chin and steel fists. Not an ounce of weakness on this character.
For a less conventional tough guy, take a look at the action flick/comedy "Mr. & Mrs. Smith." While a little bit goofy, in this film he is a professional assassin who knows his way around guns, explosives, and even a little hand to hand combat.