Who was allowed to watch the ancient Olympics?

In honor of Zeus, games were held. Crowds of all kinds of people (everyone who was interested) would gather to watch games such as discus-throwing, longjump, and running.

"Every fourth year between 776 BC and AD 395, the Olympic Games, held in honour of the god Zeus, the supreme god of Greek mythology, attracted people from across Greece. Crowds watched sports such as running, discus-throwing and the long-jump."