Thespis of Icaria (6th century BC) is claimed to be the first person ever to appear on stage as an actor in a play, although the reality is undoubtedly more complex. In other sources, he is said to have introduced the first actor in addition to the chorus.
According to Aristotle, writing two hundred years later, Thespis was a singer of dithyrambs (songs about stories from mythology with choric refrains). Thespis supposedly introduced a new style in which one singer or actor performed the words of individual characters in the stories, distinguishing between the characters with the aid of different masks.
This new style was called tragedy, and Thespis was the most popular exponent of it. Eventually, in 534 BC, competitions to find the best tragedy were instituted at the City Dionysia in Athens, and Thespis won the first competition.
It is sometimes implied that Thespis invented acting in the Western world, and that prior to his performances, no one had ever assumed the resemblance of another person for the purpose of storytelling. In fact, it is highly likely that acting had existed for thousands of years, as is indicated by cave paintings such as 'The Sorcerer'. Thespis is, however, the first known actor in written plays, as opposed to improvised or orally transmitted plays. He may thus have had a substantial role in changing the way stories were told and inventing theatre as we know it today. In reverence to Thespis, actors throughout western history have been referred to as thespians (cf. International Thespian Society).
In theatrical myth (or superstition), Thespis is said to exist now as a mischievous spirit, and when things go wrong in performances it is often blamed on his ghostly intervention. Like many superstitions, this belief ranges in different cases from being considered a humorous legend to being taken very seriously, with various charms and rituals being employed to either invite his approval or defend against him.