Harry Potter
Harry is the protagonist of the series. He rose to fame when, as a baby, he defeated Lord Voldemort in an encounter that left both of his parents dead. In The Goblet of Fire, Harry is forced to compete in the dangerous Triwizard Tournament when a follower of Lord Voldemort enters his name into the Goblet without his knowledge (despite the fact that he is too young to compete). Harry comes to a lot of "grown-up" realizations in book four, learning about the darker sides of the wizarding world, and finally coming face-to-face with a newly embodied Voldemort. Harry endures and witnesses great loss in book four; though he is hopeful for the future, he knows that dark times lie ahead.
Hermione Granger
Harry and Ron's best friend, Hermione is the brightest witch of her age. Her favorite thing to do is to spend time at the library reading books about the history of the wizarding world and learning new spells. She often helps Harry solve problems and practice his magic. In fact, without Hermione, Harry would likely not be able to overcome half the magical obstacles he faces throughout the series. In The Goblet of Fire, Hermione has a few sub-plots that contribute to the main narrative. She is a romantic interest of Viktor Krum, a famous Quidditch player and Durmstrang Triwizard champion, which stirs jealousy in Ron (and foreshadows that Hermione and Ron will develop a romantic relationship later in the series). She conducts research to help Harry with each challenge, and she also takes it upon herself to investigate how Rita Skeeter manages to overhear so much private information without actually being present. Perhaps most significant to her character development is Hermione's newfound awareness of the mistreatment of house-elves and other non-human magical creatures in the wizarding world; she starts an organization called S.P.E.W. to address the inequality and disenfranchisement of elves.
Ron Weasley
Ron is Harry's best friend and the youngest Weasley brother. Though usually 100% on Harry's side, in The Goblet of Fire Ron grows jealous of Harry's time in the spotlight. When Harry is chosen as a Triwizard Champion, Ron believes that he entered himself without sharing his method of entry. Ron thinks, for a short while, that Harry entered the competition as a way of gaining more attention than he already has. However, after the first task, Ron realizes the danger Harry faces in the tournament and comes around to the idea that someone is actually trying to hurt Harry by entering him into the competition.
Cedric Digory
The other Hogwarts champion of the book, Cedric Diggory, is a Hufflepuff. He is strong, brave, and intelligent. His father works alongside Arthur Weasley at the Ministry of Magic. Harry and Cedric decide to share their Triwizard victory by each grabbing the Cup at the same time. However, the Cup turns out to be a portkey, and Cedric is murdered by Wormtail when they enter the graveyard at the end of the book.
Victor Krum
Krum is the champion of Durmstrang Institute. He is a star quidditch player and Ron's hero at the beginning of the book, but when Krum asks Hermione to the Yule Ball, Krum becomes something of a romantic rival to Ron. Krum is controlled with the Imperius curse in the maze and thus is forced by Barty Crouch Jr. to torture Cedric until Harry finds them and stuns Krum.
Fleur Delacour
Fleur is the champion of the French magical school, Beauxbatons. Fleur is characterized primarily by her physical appearance. She is described as being extremely beautiful; her grandmother is a Veela, a type of magical humanoid whose beauty, like a siren, is hypnotic.
Mad-Eye Moody
Throughout the book, Hogwarts students believe they are being taught by Alastor Moody, an ex-Auror, however, Moody is actually Barty Crouch Jr. in disguise. Moody is a stern man, considered paranoid by many, though wizards who worked with him still respect him as one of the greatest Aurors of all time. His name comes from the glass eye he wears that can see through walls and that often spins around randomly in his head.
Barty Crouch Junior
A Death Eater that spends the book disguised as Alastor Moody, Barty is loyal to Voldemort and hopes to be the one to send Harry Potter to him. He is given the Dementor's kiss at the end of the book.
Reeta Skeeter
A journalist who manipulates the truth in order to gain publicity. She causes a lot of trouble for the protagonists and spies on them by transforming herself into a beetle.
Dumbledore
The headmaster of Hogwarts, Dumbledore is a calm father figure to Harry. He has no choice but to allow Harry to enter the tournament since ancient magic dictates the law.
Hagrid
Hagrid is the friendly gamekeeper of Hogwarts. Ever since Harry was a baby, Hagrid has protected him. Hagrid loves dragons and all manner of dangerous magical creatures. In this book, Hagrid reveals that he is a half-giant, which explains his abnormally large figure. During this book, he begins a romance with the Headmistress of Beauxbatons, Madame Maxime, another half-giant.
Voldemort
Voldemort is the main antagonist of the Harry Potter books. During the fourth installment of the Harry Potter series, Voldemort is finally able to regain his true physical form and begins his war in earnest. With the help of some of his loyal supporters, Voldemort attempts once again to harm Harry Potter.
Igor Karkaroff
The ex-Death Eater headmaster of Durmstrang school, Karkaroff is regarded with suspicion throughout the book, but turns out not to be part of the nefarious plot.
Ludo Bagman
Head of the Department of Magical Games and Sports at the Ministry of Magic, Bagman is instrumental in bringing the Triwizard Tournament to Hogwarts. He has a gambling problem and tries to help Harry win the tournament throughout because he placed a bet on him in order to pay back a group of goblins to whom he owes a large sum of money.
Bartemius Crouch Sr.
Barty Crouch Sr. is a complicated figure high up in the Ministry of Magic who, despite his record of taking a hard line against Death Eaters and Dark wizards, helps free his son from Azkaban (after sending him there for a life sentence for torturing Aurors and following Voldemort).
