Although it can be difficult, your strongest defense against intimidation is to recognize that the person's behavior has nothing to do with any deficiency in you or your work.  This is especially true if the person is threatening your job or insulting you in front of co-workers. When dealing with someone like that, it's easy to believe that your work is sub-par and that you need to do more.  However, sometimes your work is just as good, if not better, than that of your co-workers. The anxiety can lead to exhaustion when increased effort doesn't alter the bully's behavior. Observe the person's actions when they're not talking to you to see if they treat anyone else that way. Conversely, it may be that your bully is being bullied by someone else higher up the chain, and he or she is just passing it down. This doesn't excuse the behavior, but it can help you understand it and not take it as personally. Keep in mind that you are not the problem. Bullying is about fear and control, and isn't about your work performance. Even if your work isn't as good as that of your co-workers, you don't deserve to be bullied or intimidated by your supervisor. At least until you can better remedy the situation, try to keep your interactions with the problematic person to a minimum.  While avoiding the problematic person can be especially difficult if he or she is your direct supervisor, try to keep confrontations or altercations with the person to a minimum. For example, if you're expected to turn in reports to the person, you may consider delivering them when you know he or she is out of the office, or sending them using email rather than delivering hard copies. If the person tends to be less abusive or confrontational when you are with someone else, try talking to a co-worker about the situation to see if he or she is willing to accompany you when you must interact with the person who intimidates you. If you notice any issues that you believe are related to stress caused by the bully, a psychological professional can help you talk through them and provide you with strategies to minimize the impact of the behavior.  If you're concerned about cost, you can find out if sessions are covered under your health insurance. Additionally, colleges or universities in your area may have clinics that offer free or sliding-scale services.  Some states also have free or low-fee counseling available at their state mental health clinics or through pro bono networks. Keep in mind that bullying and intimidation at work can result in serious health problems if your anxiety and stress levels aren't monitored effectively. As much as you might like to stand your ground, in some cases the best thing for your health is to move on to a less hostile environment.  Particularly if the person you're having problems with is also your direct supervisor, you may have difficulty advancing in your company if he or she has it out for you. Looking for other opportunities doesn't necessarily mean you have to leave your company. If you like where you work – except for the one person – you may be able to make a lateral move to a different department, or switch to a different shift or a different working group that's supervised by someone else. If you apply at another company and are asked for references, you might want to use someone other than the problematic person, if at all possible. If there's no way around listing his or her name, keep in mind employers are legally limited in terms of what they can say about an employee.  Even though someone is engaging in intimidating behavior, state laws typically prohibit him or her from knowingly giving false information about your job performance or work history to a potential employer.  Remind yourself that moving to another job or company doesn't mean the bully "wins." Rather, it means you care more about yourself and your health and well-being to allow yourself to remain in that situation.

Summary:
Avoid taking the behavior personally. Keep your distance. Consider talking to a counselor or therapist. Start looking for other opportunities.