Murphy and Connor McManus from Boondock Saints. At first they are just your simple Catholic Irish twins who love to drink and work at a meat factory. After a bar fight on St. Patrick's Day, the two had to defend themselves and kill two members of a Russian Crime Syndicates. While in a jail cell only to hide from the press even though was not charged due to self defense, they have a vision to rid Boston from those who are wicked.
Agent Paul Smecker is an FBI agent who investigates all the cases in the movie, and he is really great at it. Through out the movie he bags on Detective Greenly because he has some stupid theory, even though he was right about one guy with six guns. He helps the brothers take out Papa Joe at the trial.
David Della Rocco, aka Funny Man, use to be a package boy for the Yakavetta family since high school until he was double crossed. He then decided to help his close friends, the McManus brothers, to wipe out the Yakavetta crime family. When the attempt to take out Papa Joe fails, he was shot in the chest and passed on.
When the Yakavetta family needed one of their own wiped out, they hire Il Duce. He was hired to take out Rocco and the brothers when they went to kill the hitman. He comes again to kill them at Papa Joe's mansion, but he realized the brothers were his son because of the family prayer. After that, he joined the brothers and execute Papa Joe at his trial.