Mary's Ex-Boyfriend, also known as Boss, appears in "Gary in Love." As his name indicates, he used to be Mary the Snail's boyfriend. He appears very dangerous because of his numerous threats to Gary. He also has his own gang with other dangerous snails. At the end of the episode, he apologizes to Gary about being mean to him and invites him to dinner.
Boss has a purple shell with a blue swirl and blue dots. He has olive-colored skin and wears a brown hat. He and his gang's meows are translated into English for the audience's sake except for when he's talking to a pet store owner.