Agatha's great-great-great grandfather, Iscarriot Heterodyne, "Everyman's "Friend" (he collected at least the craniums of 101 of them), was an infamous madman and despoiler of peaceful villages. Interestingly, Iscarriot's madness seems to have cushioned his self-image, convincing himself that he was a something of a "people person." Obviously, "Iscarriot" Heterodyne was named after this infamous personage.