Who is Hamlet?

Hamlet is the Prince of Denmark, son of the late King Hamlet and Queen Gertrude.  His mother, however, remarried shortly after his father's death, and his new step-father is actually his uncle (his father's brother), Claudius.  Hamlet is a student at the university in Wittenberg, and he is still very much in mourning over the loss of his father and the hasty remarriage of his mother.  He is very close friends with Horatio and, at the beginning of the play, the lover of Ophelia.  It is the ghost of Hamlet's dead father whose appearance so alarms the sentinels at the beginning of the play and initiates the action.  His father's ghost charges him to seek revenge on Claudius for murdering him with poison in the garden, and it is this instruction, to exact revenge on his father's murderer, that motivates Hamlet for the remainder of the play.