More than 1,000 performing artists took part in the Festival of Dionysus, yet none of these theater performers were originally considered actors.

Dithyrambs, an early form of Greek theater, were performed by choral groups of 50 men and 50 boys from the different Athenian tribes who would sing and chant the playwright's words in unison. These performances were led by a choregos (lead chorus member) and accompanied by an auletes, a musician playing an aulos (a wind instrument with similarities to a modern oboe).

By 534 BCE, the poet Thespis began performing a specific role distinct from the chorus in his plays, establishing the basic concept of an "actor" (today, actors are also known as "thespians"). The works of other Greek poets, such as The Odyssey and The Illiad, were also influential in the evolution of theatrical performance, both thematically, and as a template for rhythmic line delivery.

With the addition of an actor to the chorus, new types of theater developed: tragedies, comedies, and satyr plays, each requiring choruses of different sizes. The playwright Aeschylus (524-455 BCE) standardized using a second actor, until finally the accepted convention in Greek theatre was three actors. Though masks and costumes allowed the three actors to take on multiple roles, comedies and tragedies often featured other characters (nurses, advisors, guards, attendants—the kopha prosopa, or "silent faces") who did not speak.

Originally, following the tradition set by Thespis, the playwright would perform as the lead actor in his plays. The playwright Sophocles (496-406 BCE), was the first to step aside and employ professional actors. In the theater, focus gradually shifted from the choregos, poet, and chorus to the actors. By the 440s BCE, actors would be recognized with festival awards, form the "Artists of Dionysus" guild—and become "stars."