Of the ones we see on tv, Sammy the Bull and Leonetti are the ones who seem to have no remorse about anything they've done. I remember one interview where Leonetti explained how he killed his wives ex boyfriend. When the interviewer asked if it complicated the relationship, he seemed surprised and didn't really know what to say, like it never even occurred to him before. I don't know if either are psychopaths in the medical sense, but certainly extremely cold-hearted guys.