The Italian mafia family that targets the Shelbys in season 4 is the Changretta family.
The conflict begins as a vendetta rooted in an earlier episode of violence involving the Changrettas and the Peaky Blinders. Luca Changretta, played by Adrien Brody, travels from New York to Birmingham with the aim of destroying the Shelby family. His campaign makes the fourth season one of the show’s most direct revenge stories.
The Changrettas are fictional characters within the drama, although the series places them in the wider world of organised crime and Italian-American gangster networks. The family name is often confused with Maranzano, a real historical crime figure, or with fictional mafia families such as Corleone and Soprano. Those names are not the family targeting the Shelbys in season 4. The Changretta storyline also helps push Tommy and his relatives into a temporary alliance against a common enemy.