The three boarders are the three people who rent rooms at the Samsas' house. They are meant to represent society, and how cruel and unforgiving society can be. The middle boarder is the one who talks the most, but he conveys the thoughts that the three boarders are supposed to be having. The boarders are minor characters in the book, but their role is to challenge the authority of Mr. Samsa once he has re-established his authority as the head of the household.
