While it's difficult to say with absolute certainty, Thespis is credited with being the first to introduce a single actor (the "hypokrites") who interacted with the chorus, around the 6th century BC. This marked a significant development in the evolution of Greek theatre, moving away from purely choral performances.
However, it's important to note that:
* Ancient sources are limited: We rely heavily on fragments and accounts from later authors, so our knowledge of Thespis is incomplete.
* Other playwrights likely existed before him: It's possible that earlier dramatists existed, but their works haven't survived or have been lost to time.
Despite these caveats, Thespis remains a pivotal figure in the history of theatre, recognized as a pioneer who significantly influenced the development of Greek drama.