
Masks in theatre originated from Western Theatre, in Athens, Greece. Very well known masks are "The Janus Masks" or also known as the "Comedy Tragedy" masks. These masks were very common in the uprising of theatrical masks. All plays were either comedies, or tragedies, in honor of the god Dionysus.
These days, the detail and care of masks is much greater than it was so many years ago in Western theatre. While the Janus masks are composed of a frown and a smile, there is now a wide variety of masks used in theatre. To create these masks, latex, adhesives, creme, and much more are used to portray a character.
On that note, it is safe to say that masks are used in theatre for a common goal. This common goal consists of portraying a character, either in its emotions or unnatural physical appearance. Masks are used in situations when gestures and physical acting is just not enough.
Theatrical masks are used in The Lord of the Flies when the savages act out the killing of the pig.