In Richard Nixon v. Supreme Court are the main characters only Nixon and the Supreme Court?

Essentially, yes.

http://en.wikipedia.org/wiki/United_States_v._Nixon

In the case of Richard Nixon v. Supreme Court, the main characters involved are indeed Richard Nixon and the Supreme Court. However, it is important to note that Supreme Court cases involve many more individuals and entities beyond just these two.

To understand the key players in a Supreme Court case, we need to consider the parties involved. In this case, Richard Nixon, who was the 37th President of the United States, was one of the parties. The Supreme Court, as an institution, is also a party in this case. However, it is not a person but rather a judicial body composed of nine justices.

Beyond Nixon and the Supreme Court, there are other important figures involved in this particular case. For example, the case may include attorneys representing both parties who advocate for their clients' interests before the court. Additionally, other individuals and organizations, such as interest groups, may file briefs or provide amicus curiae ("friend of the court") submissions, expressing their opinions and arguments related to the case.

So while Nixon and the Supreme Court are indeed central figures in Richard Nixon v. Supreme Court, it is essential to recognize that there are generally multiple actors involved in any Supreme Court case.