Quintus Callus Roscius (c. 126-62 B.C.) was of free birth in the Sabine region of the Roman Empire. He became the greatest actor of his time. His grace was unrivaled, as were the mellifluence of his voice, depth of his conception of character, and subtlety of his delivery. He became a friend of Cicero. Cicero reportedly took lessons from him, and they often competed to see who could better express an idea or an emotion.
Roscius became wealthy enough to retire from the stage at an early age and to do as he wished. And so his acting career was relatively shortlived. But his name has had a surprising longevity: Today its adjective form, Roscian, is still used to express high standards. It is an eponym for perfection in acting. His name is a byword for a great actor. A Roscian performance is one of superlative skill.
Shakespeare acknowledges the superiority and versatility of Roscius’s work in Henry VI, part 3: «What scene of death hath Roscius now to act».