Professor Mezzasalma is a former Castle Heterodyne prisoner, though it has not been revealed what he did to get himself sentenced to Castle duty. He has thick short black hair and dark olive skin, and wears a blue vest. He appears to be a minor spark specializing in electromechanical systems, such as the spider-like (though hexapodal) legs that serve as his lower body. He has been seen [ to use at least one leg to hold a cable] [[Chronology - Volume #|✣ ]], suggesting that all six may be functional manipulative limbs. According to the novel Agatha H. and the Voice of the Castle, his first name is Caractacus.