Masks were used in ancient Greek plays to identify the characters and to amplify the voices of the players on stage.  As theater progressed, masks were worn to produce an alternate identity, both in serious drama and comedy.  The word mask is derived from the Arabic maskharah, meaning a buffoon.  Clowns paint their faces to create a character.  In 16th century England, masks were worn to elaborate dramatic entertainment based on mythical or allegorical themes, often without speaking parts.   The commonly used masks of comedy and tragedy have instant recognition as symbols of the theater as much as the skull and crossbones on a label identify it as poison.  Highwaymen and villains used masks to disguise their identity as well as using it for a protection to avoid detection and apprehension.  Shakespeare's plays feature the mask as motif.  In Love's Labour's Lost, he writes, "We will every one be masked".  The Bard would often turn a word or phrase as a gem cutter turns a precious stone to view the different facets of the stone he had cut.  Shakespeare would layer meanings, one after the other, putting on one mask after another like nesting boxes, like a play within a play.

In Hamlet, the protagonist must awaken to the fact that things are not what they seem. Beneath the surface, all the people who figure in his life are wearing false faces.  Hamlet must detect and uncover mask after mask in both word and deed.  His perturbation grows as he realizes the full extent of the masking around him.  He realizes he has been fooled by most of the people near him. Up until the time of his father's ghostly appearance, he seemed not to recognize this, and though he hates their phony behavior, he finds that he must don the mask of deception and slip into the guise of madness and buffoonery.  What starts as a mousetrap soon snaps upon them all.

The play opens with an elaborate mask.  The late king, Hamlet's father, appears to him as a ghost.  He tells Hamlet that his brother, Hamlet's new stepfather, was the instigator of his death, that he was poisoned, “a foul and most unnatural murder".  This revelation is quite an eye-opener for Hamlet, not unlike Adam and Eve's eating of the "apple" in the Garden of Eden.  Ever after, Hamlet finds himself east of Eden.  Though he is stunned by the ghost's message and seems to believe it, he later suffers from self-doubt and second-guessing.  Perhaps, he thinks, the spirit was but a mask of Satan or was his imagination, a conjuring begotten from his weakness and grief.  Still, the damage is done to Hamlet's innocence.  From that point onward, Hamlet furiously works at uncovering the masks of pretension from those around him.

The King, formerly Hamlet's uncle, and, now his stepfather, turns out to be Hamlet's worst enemy.  He masks his intentions at the introduction of the play, contriving to con the people into accepting his hasty marriage to Gertrude, playing the double part of the bereaved brother as well as the happy newlywed.  He gives all appearances of wanting the best for his stepson, but he considers Hamlet too dangerous to live and makes plans to have him killed in England.  The King understands his own duplicity well.  He and fellow plotter Polonius scheme to draw Hamlet out by using Ophelia as bait for their trap.  Although he is not convincing in his qualm of conscience, he says in an aside, speaking of his own hypocrisy,, "The harlot's cheek, beautied with plastering art/ Is not more ugly to the thing that helps it/ Than is my deed to my most painted word." (Act III, Scene I, Lines 51-53).  Later on in the play, the King does another take on the theme of the mask, deploring Ophelia's mental state, which he believes contributed to her death.  He says, "...poor Ophelia, / Divided from herself and her fair judgment, / Without the which we are pictures, or mere beasts" (Act IV, SceneV, Lines 79-80).  The King compares human reason to an instrument of elevation without which people are simply brute beasts, the human face covering the beast within as does the flesh over the naked skull.

When the king decides to employ Laertes to kill Hamlet, he puts on his most effective mask. He convinces Laertes that he must kill Hamlet as a point of honor for the death of his own father.   He sets the trap that will be his own undoing. By this time, Hamlet has seen the real face beneath the King's mask.  He has discovered the letter carried by the equally false Rosencrantz and Guildenstern.