The Mask.

What It is a Mask?
A Mask it is a protection, usually worn to the front of the head.
What It is the Head? The body part that contains the brain, the mind of every living being, the Head is the most communicative part of the body, containing the face, its muscles, eyes, nose and mouth.
The mask covers the face protecting it and preventing its reading.
A body with a mask has a unique expression, dictated by the morphology of the mask, which makes the movements of the wearer surprising and unpredictable, not being possible for us to read the actor’s intentions in advance through the face.
The Mask renouncing to the face enhances the movement of body language.

So deeds and actions describe the nature of a Mask, amplifying the results.
Thus, for being Higher Beings, in the Good and the Evil, Super Heroes or Super Villains, but also to break away from simple human gestures, and do something higher than normal, you must wear a Mask.
For this usually is a Monster mask.
The Mask also becomes a way to send a single message from the beholder, that of its unique facial expression.
That’s why the Mask, in its various forms of theatricality, becomes a way to build stereotypes: grotesque characters.
But, for its inhumanity, the Mask with his frozen expression can also remind Death, that’s why it always inspires fear.
Since ancient times, the wearer tries to be what the mask shows, hiding his human identity.
The Mask is the face of the monster, which, with his unpredictability is dangerous and renouncing to facial communication, is separated from the human being, often becoming a humanoid. Something that looks like a man but is not.
The classic humanoid robot is the representation of the Mask that comes to life with its independence and mobility, and approaches the role of the Man, and with it all the fears that follow.
Those who usually stand between Life and Death, on the borderline, tend to wear a Mask of the Devil, like the ancient African Medicine Men. The ones who manage the life  usually wears a Mask of Death.The scariest Mask always reminds somehow the shape of the human Skull.
That’s one of the reasons why Kubrick in Eyes Wide Shut imposes the Mask to all the participants of the Secret Society party in the villa, using Arthur Schnitzler’s narration (from which he was inspired) to describe a part of human society, with its hidden monstrosity.