Greek theater originated with Thespis, who was the first actor to step out of the chorus to narrate stories. Sophocles further developed tragedy into a high art form, focusing his plays on humans influenced by the gods and using them to teach moral and social lessons. One of his most famous works was the Oedipus Cycle, which told the story of the great King Oedipus and how he unknowingly violated societal rules by killing his father and marrying his mother.