Thespis, from whose name we get the term "thespian", was an actor who created lavish robes for the main characters in Greek tragedy in the 6th century BC.
Stylised masks, made of linen, cork or wood, were carved and painted to show age, sex, station and mood to audiences sitting in huge amphitheatres. By the 2nd century AD, more than 30 designs were in use.
Roman theatre used more grotesque faces, with attached wigs, as shown here. The wide-open mouth helped project the voice.
Roman society was famously scanalised by the Emperor Nero acting before his court. He wore naturalistic masks modelled on his own features or those of women he was in love with, including his dead wife Poppaea Sabina.
Was it the confusion between actuality and performance, the summoning of a dead personality, the blurring of status or the power of drama itself which so disturbed ancient Rome?
Then as now, masks seem one of theatre's most potent tools for eliciting the thrill of otherness, what Brecht called the "alienation effect".