The play Hamlet is full of deceit. Who attempts to deceive whom?

In Hamlet, Denmark is a prison and a
police state full of spies.  The King and Prince vow revenge against each other, and en
entire family gets caught in the crossfire.  The Prince only appears to be mad, but his
girlfriend really is.  There is one true friend of the Prince (Horatio), fake friends
(Rosencrantz and Guildenstern), and friendly players and clowns who tell the truth in
riddles.  In sum, no one is who he appears to be.  Or not to
be.

Some choice lines that deal with
deception:

Hamlet tells R &
G:

I
tell you,
must show fairly outward, should more
appear like
entertainment than
yours. You are welcome: but my
uncle-father and aunt-mother
are
deceived.

AND

Hamlet
tells Ophelia, "I loved you not."  Ophelia
responds:

I was the
more
deceived.

Hamlet
writes to Ophelia:

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Doubt truth
to be a
liar;

And
the Player Queen says:

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That I
distrust you. Yet, though I
distrust,
Discomfort you, my
lord, it nothing must:
For women's fear and love holds
quantity;
In neither aught, or in
extremity.

• Hamlet
  deceives all by appearing to be mad, even the Ghost.  The Prince was instructed to leave
  Gertrude to heaven, but he still threatens violence against his
  mother.


• Claudius deceives all, except Hamlet.  His
  behavior at the Mousetrap is a confession brought on by art.  "The play's the thing to
  catch the conscience of the king."


• Polonius deceives his
  family by using them as pawns for spying.


• Gertrude is
  deceived all men, even Hamlet.  She thinks he's
  crazy.


• Rosencrantz and Guildenstern are deceived by
  Hamlet.  The Prince switches the letter of execution, and they die
  instead.


• Ophelia is deceived by all men, especially
  Hamlet, who misdirects his anger toward his mother onto her in the "get thee to a
  nunnery speech."


• The Ghost deceives Hamlet for a while.
   The Prince cannot tell if he is a demon or a soul trapped in
  Purgatory.