King Henry IV
Henry is the king of England. He used to be Henry Bolingbroke, a nobleman, but rose to the throne when the prior king was dethroned. When the play opens, he expresses his wish to lead a contingent of warriors to the Crusades, but he can't because he is facing an armed rebellion. He is under tremendous stress from this clash of duties and the threat of civil war, but also because he is tremendously disappointed in his elder son; in fact, the king wishes Hotspur were his son. Despite this difficult situation, King Henry shows himself throughout the play to be royal in manner and a fine tactician. He expresses a strong religious intention in his opening speech, but he never returns to the topic at any length. His chief concerns seem to be his country, his throne, his desire for peace and order, and his family.
Prince Hal is also called Prince Henry, Harry, or Harry Monmouth. He is the Prince of Wales and his father's heir. He should be king someday. However, in the beginning of the play, he neglects his duties as a prince and warrior. Instead of helping restore order to the kingdom, he carouses with a bunch of drunken thieves. He even goes so far as to rob them himself. Despite this apparent neglect of duty, Prince Hal has a plan: to act the part of an idle partier and then astonish everyone by revealing himself to be a true prince and warrior. Prince Hal drinks and wastes time during the early acts and then, roughly midway through the play, reforms and becomes both a loyal son and a heroic warrior. He kills Hotspur in Act V.
Falstaff drives the play's comic subplot. He is like a second father to Prince Hal, but except for being older and male, he is exactly the opposite of King Henry IV. Whereas the king is sober, businesslike, responsible, and a strong warrior, Falstaff is a fat, lazy, dishonest drunk. He sleeps with prostitutes and robs travelers who are on a religious pilgrimage. He is completely self-interested. But he serves as a significant point of comic relief in an otherwise very serious play.
Hotspur is also called Harry, Sir Henry, and Harry Percy. He is Prince Hal's counterpoint; when the play starts, he is the young warrior King Henry IV wishes were really his son, and he is on the king's side against the rebels Douglas and Glendower. But after the king insults his honor, Hotspur joins the rebellion and becomes one of its leaders. As his name suggests, Hotspur is passionate and rash. He reacts quickly, moving rapidly from position to position, talking himself into and out of a decision in a matter of minutes. He thinks of himself as realistic; this is seen most clearly in his arguments with Glendower. However, he is driven mainly by emotion and his sense of honor.
Sir Walter Blunt
Sir Walter Blunt is characterized by his steadfast loyalty. As his name suggests, Blunt says what he thinks, and his word can be trusted. The king trusts him to carry messages to and from the rebel leaders and to negotiate on the crown's behalf. In the play's climactic battle, Blunt fights disguised as the king, and Douglas kills him.
Douglas is more straightforward than other rebel leaders. He will not engage in devious behavior. He is brave, and late in the play he kills a disguised Sir Walter Blunt, thinking he is the king.
Glendower sees himself as a hero in the classical tradition. He claims that portents of his greatness appeared on the day he was born and that he has supernatural powers (control over demons and spirits). He is a fierce warrior, but he gives no proof of his supernatural abilities. He is father to Lady Mortimer and clearly loves her.