Alex Deuyour – An 14 (nearly 15) year-old British-American and the brains of the group, who is put into the Triwizard Tournament against his will.

Harry Potter – A 14-year-old wizard who was responsible for Voldemort's downfall thirteen years ago.

Ron Weasley – Alex's godbrother and second cousin and one of Alex and Harry's best friends who is loyal, but in this book, he finds himself being jealous, first of Alex and Harry being in the tournament and later when Hermione dances with Viktor Krum at the Yule Ball.

Hermione Granger – Alex and Harry's other best friend and the other brains of the group.

Kate Nguyen – Alex's crush and best friend, who he dances with at the Yule Ball.

Matt Crocitto – Alex's best friend and a half-blood Gryffindor.

Lord Voldemort – Alex and Harry's arch-nemesis, who is plotting his return. This causes Harry's scar to hurt frequently throughout the book.

Sirius Black – Alex and Harry's godfather, and Alex's maternal godfather, who can turn into a dog Animagus, at will. He returns to Hogwarts to help Alex and Harry for the tournament and gives them information about Karkaroff and the Crouch family.

Rubeus Hagrid – The Gamekeeper and Care of Magical Creatures who is a good friend of the group. He has a fondness for dragons and starts a romantic relationship with Beauxbatons Headmistress Madam Maxime.

Peter Pettigrew / Wormtail: Voldemort's loyal servant who betrayed and indirectly killed Harry's parents by giving them to Voldemort.

Albus Dumbledore: The Headmaster of Hogwarts who is wise. He begins getting suspicious and unnerved after Harry's name is put in the Goblet.

Alastor "Mad-Eye" Moody: An grizzled and paranoid ex-Auror and the new Defense Against the Dark Arts teacher at Hogwarts. He is revealed to be Barty Crouch Jr. in disguise, and the real Moody was locked in his trunk for the whole year.

Ludo Bagman: An former Beater for the Wimbourne Wasps and the Head of the Department of the Magical Games and Sports, who has a gambling addiction and is dimwitted somewhat, being accused of giving the Death Eaters information, but he will let off after the jury chalked this up to his stupidity.

Rita Skeeter: A nosy reporter who writes reputation-ruining articles about Alex, Harry, Hermione, and Hagrid.

Barty Crouch Sr.: The Head of the Department of Magical Cooperation, who was once being groomed to be Minister of Magic, until his reputation was ruined due to the scandal involving his son.

Barty Crouch Jr.: Barty's son and a convicted Death Eater, who impersonates Moody all year and helps Alex and Harry win the tournament.

Sybil Trelawney: The Divination professor at Hogwarts who makes false predictions.

Minerva McGonagall: The Head of Gryffindor House and Transfiguration professor who is strict and a fan of Quidditch.

Severus Snape: The Head of Slytherin House and Potions teacher who favors Alex as he is his godfather and honorary uncle.

Igor Karkaroff: The Headmaster of Durmstrang who was once a Death Eater and is concerned about Voldemort's impending return.

Madam Maxine: The Headmistress of Beauxbatons and a half-giant who Hagrid is smitten with.

Fleur Delacour: The Beauxbatons champion who Ron is smitten with.

Viktor Krum: The Durmstrang champion and the Seeker for the Bulgarian national Quidditch team.

Cedric Diggory: The Hufflepuff Seeker and a champion for Hogwarts who is killed by Voldemort.

Cho Chang: A Ravenclaw fifth-year who is Cedric's love interest.

Neville Longbottom: Alex's godbrother and second cousin who is a clumsy boy whose parents were tortured into insanity by Death Eaters.

Draco Malfoy: Harry's greatest nemesis at Hogwarts and Alex's first cousin.

Lucius Malfoy: Draco's father and a Death Eater in Voldemort's Inner Circle.

Ginny Weasley: Ron's shy younger sister who has a crush on Harry.

Percy Weasley: Ron's pompous older brother who works at the Ministry and is obsessed with Crouch Sr.

Fred and George Weasley: Ron's older brother who are twin pranksters who are ambitious with a joke shop. Alex and Harry give them money to start the joke shop, which is 1,000 Galleons each from both of them.

Bill Weasley: The eldest offspring of the Weasley family, who works in Egypt at Gringotts as a Curse-Breaker. He attends the Quidditch World Cup with his family and their close friends and watches the Third Task as Harry's support.

Charlie Weasley: The second eldest offspring of the Weasley family, who works with dragons in Romania. He stays at Hogwarts for the First Task to help with the dragons.

Molly Weasley: Ron's mother who is overprotective but strict.

Arthur Weasley: Ron's Muggle-obsessed father who works in the Misuse of Muggle Artifacts Office.

Winky: Barty Sr.'s house-elf who works in the Hogwarts kitchens with Dobby after being freed.

Dobby: The Malfoys' former house-elf who works in the Hogwarts Kitchen and is loyal to Harry.

Kreacher – The Black family's house-elf.

Vernon Dursley – Harry's magic-hating Muggle uncle.

Petunia Dursley – Harry's unpleasant Muggle aunt.

Dudley Dursley – Harry's overweight cousin who is on a diet.

Frank Bryce – The Riddles' gardener who is killed by Voldemort for eavesdropping.

Bertha Jorkins – A forgetful Ministry witch who went missing in Albania. She is revealed to have been killed by Voldemort.

Amos Diggory – Cedric's loyal and proud father, who boasts of his son's accomplishments.

James and Lily Potter – Harry's deceased parents who were killed by Voldemort while protecting Harry.

Thomas Deuyour – Alex's deceased father, who was killed by Voldemort during the First Wizarding War.

Argus Filch – The grouchy caretaker of Hogwarts who enjoys taking sadistic pleasure from torturing students.

Cornelius Fudge – The Minister of Magic who refuses to acknowledge Voldemort's return.

Seamus Finnigan – Alex and Harry's housemate.

Dean Thomas – Alex and Harry's housemate who is obsessed with soccer.

Parvati Patil – A Gryffindor girl who goes with Harry to the Yule Ball.

Colin Creevey – A third-year Gryffindor who idolizes Harry. His younger brother, Dennis, is sorted into Gryffindor.

Crabbe and Goyle – Malfoy's dimwitted minions.

Nearly Headless Nick – The ghost of Gryffindor Tower.

Peeves – A poltergeist who causes mischief at Hogwarts.

Moaning Myrtle – A Hogwarts ghost who haunts the girls' bathroom and has a crush on Harry.

Mr. Roberts – A Muggle who owns the Weasleys' campsite.

Bandit – Alex's pet pit bull.

Hedwig – Harry's loyal pet owl.

Pigwidgeon – Ron's excitable pet owl, who he affectionately nicknames "Pig".

Crookshanks – Hermione's half-Kneazle pet cat, who is aggressive and gets along well with Bandit.

Fawkes – Dumbledore's pet phoenix, where Harry gets his wand core from.