Posters of Viktor Krum are attached to every tent of the Bulgarian supporters at the Quidditch World Cup. Although the picture on the poster can move, all it does is blink and scowl. Ron tells Harry and Hermione that Krum is an unbelievably talented Quidditch player.
Krum is the last of the seven Bulgarian Quidditch team players to fly into the Quidditch stadium as they are announced by Ludo Bagman. During the match, Krum performs the Wronski Feint, a dangerous Seeker diversion, which causes his opponent to crash into the ground. His face is contorted with concentration as he performs the move, designed to make Aidan Lynch think he has spotted the Snitch. Krum flies briliantly, and it seems to Harry as though he is hardly using a broomstick at all; he moves so easily through the air it appears as though he is unsupported and weightless. Krum circles high above Lynch as the mediwizards revive him, using the time to search for the Snitch without interference. As the match continues Krum is hit in the face by a Bludger, breaking his nose, but before the referee has time to notice Krum spots Lynch hurtling downwards after the Golden Snitch; Krum tails Lynch and draws level with him as Lynch crashes into the ground a second time, but Krum mananges to catch the Snitch, ending the game. His robes shine with blood from his nose as he rises gently into the air, his fist held high, the Snitch a glint of gold in his hand. Harry thinks that Krum wanted to end the game on his own terms, as he knew the Irish Chasers were too good for the Bulgarian team to be able to win. He looks surlier than ever when he returns to the pitch, and refuses to let the mediwizards clean him up.
Krum files into the Top Box with the other Bulgarian players to shake the hands of the two Ministers for Magic. Up close, he looks a real mess, with two black eyes blooming on his face. Krum appears much less coordinated on the ground; he is slightly duck-footed, and is distinctly round-shouldered. The stadium gives him a resounding, ear-splitting roar of approval when it is his turn to approach the officials.
Viktor Krum is a student at Durmstrang wizarding school. He is ushered forward by Professor Karkaroff after Karkaroff has greeted Dumbledore, and is led into the warmth of the castle; he has a slight head-cold.
Krum enters the Great Hall with his fellow Durmstrang students and takes a seat at the Slytherin table. He and the Durmstrang students are to sleep on the Durmstrang ship during their stay at Hogwarts.
Viktor Krum is chosen by the Goblet of Fire as the Triwizard champion for Durmstrang. When his name is called, Krum walks through the Great Hall amid thunderous applause and into the small room off the side of the Hall.
Krum is leaning against the mantelpiece in the room off the Great Hall when Harry enters. He straightens up when Ludo Bagman introduces Harry as the fourth Triwizard champion; his surly face darkens as he surveys Harry. He is confused when he hears that Harry's name came out of the Goblet of Fire.
Krum leaves the room with Professor Karkaroff after the information about the First Task has been given by Barty Crouch
Krum stands moodily in the corner of the classroom in which the Weighing of the Wands is taking place as he waits for the ceremony to begin. He scowls as he hands his wand to Mr Ollivander, and stands with his hands in the pockets of his robes as he waits for the wizard to examine it. Krum's wand is a Gregorovitch creation, ten and a quarter inches long, made of hornbeam and dragon heartstring.
Krum skulks, half-hidden, at the back of the group during the photograph portion of the ceremony.
Krum spends a lot of time in the library at Hogwarts. Harry is usure whether he is studying, or whether he is looking for things to help him through the first task. Krum is often spied upon in the library by groups of giggling girls, who hide behind the bookshelves.
Viktor Krum picks the Chinese Fireball dragon as his opponent in the first task of the Triwizard Tournament. He is the third champion to attempt the first task. Ron says that Krum did very well in the task, although he didn't attempt to fly. He hit the Chinese Fireball with a spell right in the eye. Although it was effective, Krum had marks deducted because the dragon trampled half of its real eggs in its agony. He tied first with Harry for the first task, with forty points.
Krum takes Hermione to the Yule Ball as his date. The pair enter the Great Hall with the rest of the Durmstrang students, leading the group. Krum leads Hermione to the top table for dinner. He tells her enthusiastically about the Durmstrang castle and the students' life at the school. He has difficulty with Hermione's name, and keeps calling her 'Hermy-own'. He eventually progresses to pronouncing her name 'Herm-own-ninny'. After dinner, he and Hermione join the other champions on the dance floor for the opening song. The pair continue to dance together as the other students join them on the dance floor.
Viktor emerges onto the deck of the Durmstrang ship as Harry, Ron and Hermione are walking by. He is dressed in swimming trunks; climbing up onto the side of the ship, he stretches his arms out and dives right into the lake.
Krum waits at the judges table by the lake, waiting for the second task to begin. Krum attempts to Transfigure himself into a shark for the task, to allow him to breathe underwater. He is partially successful, but it is not a good Transfiguration: he retains his human body, but has the head of a shark. His new teeth are positioned very badly for biting anything smaller than a dolphin, and he is in danger of harming Hermione as he tries to bite at her ropes. Krum is hit on the shoulder by Harry, who hands him a jagged stone; seizing it, Krum begins to cut Hermione free from the statue of the merperson. Once she is free, Krum grabs her around the waist and swims towards the surface of the lake. Krum is the second champion to return with their hostage. He is awarded forty points for the task.
Viktor meets Ludo Bagman and the other three champions in the centre of the Quidditch pitch to find out about the third task. He is informed that he will enter the maze third, after Harry and Cedric. On their way back to the castle, Krum asks Harry to walk with him, keen to talk to him. Instead of making his way towards the Durmstrang ship, he walks towards the Forbidden Forest, telling Harry he doesn't want to be overheard. Krum wants to know what feeling there is between Harry and Hermione, following the article by Rita Skeeter, and is suspicious about why Hermione talks about Harry so often.
Krum is surprised when Barty Crouch appears from behind a tree in the Forbidden Forest. He vaguely recognises the Triwizard Tournament judge, and is alarmed by the way Crouch is acting. He waits with Crouch whilst Harry runs to fetch Professor Dumbledore, and tells Harry to hurry, worried about being left with a mad-man. Krum is Stunned as he waits for Harry to return, and is sprawled, unconscious on the Forest floor when the teachers arrive. Krum tells Dumbledore that Crouch attacked him from behind when he turned to see where Harry had gone.
Krum is greeted by his parents in the chamber off the Great Hall on the morning of the third task. He takes after his father, having inherited the same hooked nose and dark hair. Krum talks to them in rapid Bulgarian in a corner of the room.
Krum makes his way to the Quidditch pitch with Ludo Bagman and the other three champions after the evening feast. He is introduced to the crowd by Ludo Bagman, and enters the maze third, in accordance with his number of awarded points. During the task, Krum performs the Cruciatus Curse on Cedric Diggory, standing over the boy as he twitches and jerks on the ground. He attempts to run when Harry discovers him, but is Stunned by Harry and stops dead in his tracks. The spot where Krum lies is marked by Cedric and Harry by sending red sparks into the air, to alert the teachers patrolling the maze.
Krum attends the Leaving Feast with his fellow Durmstrang students. They are encouraged by Professor Dumbledore to embrace the ties promoted by the Triwizard Tournament, and are invited back to Hogwarts should they ever want or need to come.
Krum joins Harry, Ron and Hermione in the Entrance Hall to say goodbye to Hermione. He asks to speak to Hermione alone, and the pair walk away from the crowd and out of sight. When the pair return soon after, Krum tells Harry that he liked Cedric Diggory; the boy was always polite to Krum, even though he was from Durmstrang. Krum scowls as Harry asks whether they have a new headmaster yet, and shrugs indifferently. He is surprised but gratified when, just as he is walking away, Ron asks for his autograph, and signs a fragment of parchment for him.