The Godfather was mostly fiction, but based on alot of true events and families. For the most part It was based on the Bonnano Family Giuseppe ( Joseph or don Pepino ) Bonnano, for Vito. And his son Salvatore ( Bill ) Bonnano as Micheal.

If you read both of their autobiographies, you will see many, many simalarities from their lifetime stories to the Godfather.

Joseph Bonnano - A Man of Honor
Bill Bonnano - Bound By Honor