Thank you very much, Gemini. :)

If you ask him to stop a behavior because you find it abusive and he continues, you are being abused. If HR does not resolve the issue then the company can be sued for allowing harassment and a hostile workplace. Document everything you can and inform your supervisor of the status of the situation regularly.

It's tough, but it can work. It sounds like this guy doesn't have a lot of friends. That makes the situation immensely easier. When you try to take this route with influential people, it is extremely difficult.

I realize this thread is dated, but it should be mentioned.

The good thing is he gets on many peoples nerves and it looks bad that he caused other people to quit. I think you should go in a group to complain to the boss,follow up in a polite and tactful way. Like the other person said keep a paper trail.