Greene is introduced in "The Godfather" as a renowned Jewish mobster and former executioner for Murder, Inc. He is credited with the development of gambling and entertainment in Las Vegas and bringing the interests of the most powerful organized crime organizations in America to Nevada. Greene is in business with Don Vito Corleone, who bankrolls the creation of Greene's first hotel-casino. In return, Greene takes the Don's second son, Fredo Corleone, under his wing during the war between the Five Families in New York, with the Molinari Family guaranteeing Fredo's safety. Although Fredo is greatly influenced by both Greene and the city, family heir Michael Corleone disapproves of the effect it has on his brother, whom Greene reportedly chastised and slapped around in public.