King Henry IV
Henry IV is the ruling king at the beginning of the play, but he has grown sick and weary. He is plagued by insomnia because of his guilt over usurping Richard II, anxiety from the constant uprisings, and concern over the kind of king his son will be. He wishes to go on a crusade to expiate his guilt over deposing and killing the former king, but constant insurrections and his own poor health prevent him from doing so. He is so concerned with Prince Hal's abilities to lead that he asks his other sons to do their best to temper their brother once he takes the throne. Prince Hal and King Henry IV reconcile before the king dies, giving his son the political advice to focus on foreign wars as a way to keep his nobles in check. He knows that the laws of succession will afford Hal an easier time as king than he had.
Prince Hal (also called Harry, Prince Henry, Prince Harry) is the young, wild heir of King Henry IV. Despite his promise to reform at the end of Henry IV, Part 1, he still seems loathe to give up his dissolute ways. He still carouses and associates with his old friends, though he has distanced himself from Falstaff. He is concerned for his father's health, but because of his past actions he fears people will see him as a hypocrite. He is in the process of casting off his old persona of "playboy" and striving to figure out what it will take to be a good king. He and his father reconcile shortly before Henry IV's death. In need of a father figure and adviser, Hal turns to the Lord Chief Justice, asking the man to fill that role for him.
Sir John Falstaff is a lovable rogue. He's a liar, a conman, and a criminal, but also a knight who fought in the Battle of Shrewsbury. Falstaff is often a source of comic relief because of his constant scrapes and witty monologues. In Henry IV, Part 1 he claims to have killed Hotspur, and Prince Hal—the actual killer—agrees to go along with the lie. Falstaff has ridden that deed as far as it can take him, but the nobility and high court officials do not give him much respect. He and the Lord Chief Justice clash over Falstaff's behavior and his perceived influence over Prince Hal. He believes that when Hal takes the throne, he will be advanced as one of the most influential men in England. By the end of the play, he is a pitiable character, especially when Hal publicly renounces him. He tries to convince himself and his friends that Hal is just saving face and will call for him in private to reward him, but when the Lord Chief Justice arrests him, he realizes his mistake.
Lord Chief Justice
The Lord Chief Justice is the highest legal official in the land (barring the king). He is a calm, intelligent man, which serves him well as an adviser to King Henry IV. In the past he has treated Prince Hal no differently than any other criminal, even going so far as to imprison him for public disorderliness. He is in conflict with Sir John Falstaff. Falstaff sows chaos and disorder wherever he goes while the Lord Chief Justice values law and order. He is concerned about Falstaff's influence over Prince Hal. He is worried about what kind of a king Hal will make, and if he will overturn all of the good done during his father's reign. When Prince Hal becomes Henry V, he asks the Lord Chief Justice to remain as the king's adviser and to act as a surrogate father figure. The Lord Chief Justice then arrests Falstaff on Henry V's order, a triumph of law over chaos.