I am unsure what to do here. I work with a person that is very high energy and loud pretty much all of the time. And that's on a good day. On a bad day, this person is high energy to the point of agitation and loud to the point of yelling while people are clearly working, interrupting to ask unnecessary questions, and sometimes, confronts/upsets other co-workers with trivial issues that he deems 'critical' just to get a reaction out of them, and when he does, tells them they are overreacting and he wasn't being serious.

I understand it's really this person's issue, not mine, and for 2 years I have been pretty good at distancing myself personally from him, but yesterday he crossed a line with me and I almost lost my cool. I hate feeling that angry and helpless. He tried to get me to say and agree to bad thing s he was saying about another co-worker, and when I wouldn't, he got louder and loudeer until I said that we can just drop it, that we agree to disagree and let's move on. At that point, he started slamming equipment in our work area and glaring at me, the intention, I know, was to intimidate. So, I left the area and went into the room next door to work (I still had responsibilities of my own to complete) and at that point, he started slamming stuff into the wall between the two rooms loud enough to let me know he knew I was there, and later when he needed something he kicked my door open and snapped a demand, which I pretended not to hear, and then he slammed my door only to return with another co-worker a few minutes later and act as if nothing happened.

I really don't know what to do about this - I am a female in a male-dominated workplace and I feel like saying something makes me look weak or helpless, and I am not that at all, but I honestly feel threatened and even bullied... over something so stupid... any ideas what is really going on and what I should do? Thanks!

The options are clear: fight or flight.

You work in a hostile environment, so you have a legal case that you can take advantage of. But, before you do that, you should complain to the higher ups or HR department. If they do nothing about it, then then you have the opportunity to prove negligence on the company's part, which means you should get in touch with a lawyer and sue the company.

Option 2 is to find a new job.

In short: get legal advice STAT.

You report this to HR and to your manager, right when it happens, you demand that this hostile work place be resolved.

I have documented this incident (for whatever it's worth... I don't have a lot of confidence in my HR reps), but it truly is the first direct personal attack from him against me in a couple of years. I have seen him intentionally irritate others and agitate during group meetings, but others either ingore him or blow up at him and in either case, he gets the attention he's seeking and the storm passes for a bit. Obviously, these approaches are not helping anything.

I guess what I am looking for here is exactly how I should be dealing with a personality like this until action can be taken to make it better. I was really shocked and hurt by what he did (my problem, I know) and I need to know how to handle this while I take the necessary steps with management and HR. Does that make sense? I appreciate the responses so far and yes, I will go up the chain of command, even at my own peril :/

I would also suggest creating as much documentation of these "goings-on" as possible and filing the complaint in writing or it never happened in some minds.
Depending on laws concerning recording conversations in your area, it may be possible to get it recorded. For instance (if you can't record it openly or without consent), what if you "just happened" to be leaving a message on a friend or co-workers ans. Machine or voicemail when this jerk started his tirade and it just happened to get recorded-usable? -maybe.
Or possibly a co-worker would get such a crazy message with strange things going on in the background and report it to their supervisor?
Speaking of supervisors-where are they? They don't notice these loud disruptions?
Maybe some of your co-workers would be willing to sign a complaint too, so no one is singled out, or you are at least one of several or many.
I hope you can get some relief from this nonsense and I realize it is not always easy to do and you need to protect your job etc. If nothing else, try and create some solid evidence in case you have no choice but to make a major case out of it-at a future date. Don't rely on verbal discussions or depend on others to back you up--often neither of those options pan out.

My supervisor works different hours than we do, so interaction and contact with supervision is limited and only during certain hours, which, I've noticed, is when this person seems to be the most calm. We have mid-level management on site during our shift, and I have asked a few times to please not send this person to help me because he is being extra loud and running on hyperspeed that day, and they have agreed sometimes not to pair me up with him, but also, a couple of times, they told me to work it out like an adult and sent him to work with me, anyway. Other people in my workplace comment about whether this person is calm or agitated daily and warn each other - I try very hard not to engage in that because I've noticed it gets him going, and I honestly think that's how I've managed to mostly stay off his radar until now. I have not heard of him slamming stuff around and staring anyone down yet, but again, I try to stay out of his business because the little interaction I am required to have with him completely exhausts me, even on his best days, so I honestly don't know if this has happened before. I think trying to find out might make me look bad, too, so I don't want to ask anybody. And my direct supervisors on shift roll their eyes whenever anybody reports the emotional staus of the person in question - and hey, I understand, psyhciatry is not their job and it's not pre-school - but a little more support from them would be great. He's loud, though, and irritable, but also very skilled... to upset him could hurt the team, I think, from their perspective. He really has a great technical mind, just not emotional or social skills whatsoever. It's a tough call, because just me being a female and upset already makes me look weak and wishy-washy and he's playing a strong, loud, assertive male with great technical skill, you know, a good ol' boy when the higher ups are around.

I wondered about his skill level as I wrote my first response. I am not an expert (just experienced) in these matters. As a supervisor myself, I have to admit that I did not follow my instincts a few times because the problem employee was very technically competent. In the most recent episode (by recent I mean it happened near the end of my career, before I retired) the employee eventually self-destructed. At that time it became very clear why he had ruffled so many feathers--and I am making no inference here that your friend falls in the same category--but my employee was
Arrested for selling cocaine in his remote field office--he was fired on the spot-the state police had all the documentation anybody could possibly need. Nobody worried about his skills at that point. Once again, I am not implying that your friend is doing any such thing but it happens more frequently than I realized before that episode.
I did not follow my instincts. There is an old saying something like: if something looks right, it might be wrong but if it looks wrong it's got to be wrong. I suffered every time I failed to follow my nose on issues like this. In my situation, the subordinates of my problem employee just went along with their boss, which human beings tend to do--they brought nothing to my attention (which employees tend to do if it is someone they work for or need and rely on to keep their own work flowing).
If your friend is relied on by others or by the company, he knows it and may assume that he can do no wrong.
I don't know all of your circumstances and I don't know what your friend is capable of doing or might do in retribution, or how badly you need your job.
Maybe you should get some good legal advice. But I still feel that you need to establish some good documentation of what is going on. I have seen some strange happenings in office settings, construction projects and project field offices over a 40 yr career, but nothing quite as bizarre as you describe (maybe there were worse in my jurisdiction and it was successfully kept from me (that would be my fault) ever went on to my knowledge.
But, in my experience when these matters get to the hearing stage, the hearing officer's first question is: What rule or policy was violated-chapter and verse? And second-what evidence do you have to support the charges?
The person making the charge has to have facts to back themselves up or the tables can turn--the charger can end up being the "chargee". You can probably talk to an attorney who has experience in workplace disputes, at no charge. But I can almost guarantee that such an attorney will ask what documentation exists and if there is none, he/she may have some suggestions on how to develop some.
Allowing it to go on with no plan will simply keep you in your present position which is between a rock and a hard place.
I sincerely wish that you can find a solution which not only solves you problem but also protects your own interest.