Hamlet is full of duplicity. Claudius pretends to be fatherly even though he killed Hamlet’s father. Ophelia cuts him out of her life because she was an obedient daughter. Guilderstern and Rosencrantz were also deceptive in their friendship with Hamlet. However, Hamlet was also deceptive in his actions.
Hamlet asks Ophelia where her father is in Act 3, Scene 1. She replies with a lie: "At home, my lord."
Ophelia is well aware that Polonius and Claudius are eavesdropping on the conversation between Ophelia and Hamlet. The outcome is Hamlet's angry outburst, "Let the doors be shut upon him, that he may play the fool nowhere but in's own house." Polonius would have been well served to have heeded this warning.
Ophelia is trying to understand why Hamlet is acting the way he is and is lying in order to help him and because her father told her to do so. The result of this lie is a relationship that is permanently severed.
Polonius is certainly deceptive with Hamlet and others as he has a predilection for hypocrisy and spying. For, after giving his son, Laertes a long-winded speech on virtue, he arranges to have his son spied upon. Then, when his daughter Ophelia speaks of Hamlet, Polonius decides that the young man is mad. He goes to Claudius and informs him "You noble son is mad." Claudius agrees to spy with Polonius upon Hamlet.
When Hamlet in Act II, Scene 2, encounters Polonius, knowing what the corrupt courtier, he calls Polonius a "fishmonger" and tells him "I would you were so honest a man." For a while they banter words, then Polonius says, "My lord, I will take my leave of you." However, he later hides behind the curtain in the queen's chambers to overhear.
Another lie told to Hamlet, even though he relatively quickly exposes it, is that of Rosencrantz and Guildenstern who say they've come from Wittenberg just to see him and to enjoy his company. They know they were sent for by the King but they have to play a role, one that Hamlet points out extremely well in the later scene talking about them trying to play him as a pipe.
But that lie is certainly still used in kind today as people act as though they come in friendship when in reality they have come to gain information, whether at the orders of someone else, or simply for themselves.
Claudius sends Hamlet to England and in the process arranges for Hamlet to be executed upon arriving in England. After Claudius tells Hamlet he's sending him to England, Hamlet quips "Good," and Claudius answers that if Hamlet knew "our" purposes--thereby connecting the decision to the queen--that Hamlet would think sending him to England was a good thing. This is an obvious lie, since Claudius's purpose is to have Hamlet executed.
Everybody lies to Hamlet except Horatio.