How Can I Stop Someone From Threatening Me On The Internet?

Well, If you don't know the person and has never talked to the person, then how do I suppose they know so much about you? All websites in which there is any way of communication, there is a way to block the user from contacting you. If the person can contact you by phone, you can call your phone company and have their texts and calls blocked. If the person is able to make physical contact with you, then you can get a restraining order. In your case, which is harassment on a public discussion board, you can easily report their comments/or post. I don't think you have to go as far as calling the F.B.I., because usually these kind of people are posers and want some type of "2^nd life", or authority.

Best way is to tell them that you printed out the threats and if they don't stop, you will file charges, if the threats are life threating, you can call the f.b.I  in on this, guaranteed that will make them stop

If it's over instant messenger right click on the persons name and click on 'block' or if its on myspace go to there profile and under neath 'add' block user, and if its like really bad threats ide say call for help.

What if you know the person and they threatened to shoot you?
I called the local cops but they say nothing can be done because the guy who threatened me is on the other side of the country.

I'm having same problem,some people showed up at my house tried to beat my minor son up.do we have the right to defend ourselves in Ohio with force like fight back if we have to? People were 18 .with bat on hand.