What can I do about a supervisor who has put me in fear for my safety?

The law provides recourse for an employee who works in a "hostile work environment". In other words, it prevents them from doing their job duties reasonably. Basically, a superior and/or co-worker, either by behavior or actions, creates an environment that is counterproductive to an employee performing their work responsibilities. That having been said a person stating that they hate you, while disconcerting, most probably does not give rise to a legally actionable claim; superiors/co-workers can make rude and cruel remarks (unfortunately).
However, behaviors that are discriminatory in nature and are not merely the result of unprofessional or rude behavior, may be actionable. Accordingly, action taken against an employee because they are a member of a "protected class" is illegal. In other words if their treatment is based on race, religion, age, disability, sexual orientation, gender, national origin, etc. , they may have a claim.
Since you mentioned both your age and race, it appears that they may be a factor in your treatemnt. If so, you should consult directly with an employment law attorney or contact your state's department of labor for further information.
d on the limited facts that you have presented, it's not clear that neither plays a role in your situation. You should be aware that most employment relationships are what is known as "at will", which means that an employer can hire or fire someone for any reason or no reason whatsoever, as well has increase/decrease salary/hours, promote/demote, and generally impose requirements as they see fit. In turn, you can work for an employer, or not, your choice.
Note:  Exceptions to the above would be if there is a stated company policy covering your situation, or there is a union/employment agreement to the contrary, or (as stated above) if your situation has arisen due to some type of discrimination.

You can, and perhaps should, resign and seek other employment. While you say that the supervisor put you "fear" for your safety, the law woud not agree: saying "I hate you" or generally being disrespectul and rude is--
1) Not a crime; only threats of violence are crimes, but the law does not criminalize hating another;
2) Not something you may sue over--the law does not give you compensation for being hated; and
3) Not something which a supervisor is prevented or barred from saying--to be blunt, the law allows supervisors to hate their employees.
This is not to say that this job is a healthy or good environment for you; but it is to say that based on what you write, you do not have legal recourse.