Final answer:
The King and Queen of Denmark hire Rosencrantz and Guildenstern to spy on Hamlet and discover the reasons behind his madness.
Step-by-step explanation:
In Hamlet, it is The King and Queen of Denmark who hire Rosencrantz and Guildenstern to figure out why Hamlet has gone mad. King Claudius, Hamlet's uncle and stepfather, along with Queen Gertrude, Hamlet's mother, are concerned about Hamlet's erratic behavior following the death of his father and their swift marriage. They enlist the help of Hamlet's childhood friends, Rosencrantz and Guildenstern, to spy on him and discover the cause of his apparent madness.