Bill Ferny is the filthy spy from Bree who serves Isengard for money. He is one of the two rogues of Isengard's heroes, meant for espionage, scouting, and vandalism, rather than for combat. As this implies, he isn't really good at combat, but he has some good abilities that can really help the faction in the early game, that he will earn if you pay him gold, eventually taking matters into his own hands and becoming a good fighter for a short period of time.