Actors and actresses are called thespians
in honor of Thespis, a Greek playwright and performer. Around 535 B.C.,
Thespis added a new dimension to drama by stepping out of the Greek
chorus during a performance and reciting portions of the text alone,
becoming the first actor. He is also credited with inventing the
theatrical mask.
"It
is generally supposed that Thespis, who managed a traveling company,
transported his actors in wagons, which also served as their stage,"
according to The Cassell Companion to Theatre, which quotes this couplet from John Dryden:
Thespis, the first professor of our art,
At country wakes sang ballads from a cart.
Thespian
with an uppercase "T" refers to a member of the International Thespian
Society, the world's largest honor society for theatre students. The
designation "Thespian" includes student members who excel in technical
and production fields as well as performance in their high school
theatre.