Kostas Triantafyllopoulos (Greek: Κώστας Τριανταφυλλόπουλος; 8 February 1956 – 21 August 2021) was a Greek actor. After studying at the Theodosiadis Drama School of Athens, he graduated in 1977 and played a wide variety of roles on stage from Greek tragedy, Aristophanes and Shakespeare to contemporary American drama (Eugene O'Neill, Arthur Miller, Tennessee Williams, Joyce Carol Oates, Thornton Wilder, Sam Shepard). He performed frequently at the National Theatre of Greece, the National Theatre of Northern Greece