"It is pendejos like you and Pereiro that make the people of this land suffer such poverty. Your time has come; it is time to make a stand." -The Unidentified Boss confronts a McCall.
The Unidentified Boss was an opponent of a McCall in Call of Juarez: Bound in Blood. His real name is unknown, but the subtitles refer to him as 'Boss'.
At some point, he and his gang stole items of value from the presumably wealthy Borubaro Pereiro, who put out a $100 dollar reward for anyone who could retrieve the items and bring those responsible for the theft to justice. The man may have grown up in poverty as alluded to when he justified stealing Borubaro Pereiro's property to the man whom had come to collect the bounty.
Call of Juarez: Bound in Blood
One of the McCall brothers answered the add and located the outlaw and his gang in a cave outside San Lorenzo. The gunfighter fought through the outlaws and found their leader. The two men dueled, leaving the boss dead.
He was a well-built man in his forties, with black hair that was slicked back and a modest mustache. He wore a white jacket, blue scarf, pink shirt, black trousers, and brown boots. He carried a Ranger as his sidearm.
The man seemed to care deeply for the people of Mexico, and despised Borubaro Pereiro presumably because of the latter's selfishness and arrogance in his wealth. Likewise, he also disliked the McCall that came to return the stolen items for Pereiro.