Poliakoff was a student from the Durmstrang Institute who visited Hogwarts School of Witchcraft and Wizardry as part of his school's delegation for the Triwizard Tournament in 1994. He is a minor character whose presence helps to establish the nature and composition of the visiting Durmstrang contingent led by Headmaster Igor Karkaroff.
Poliakoff arrived at Hogwarts via the Durmstrang Ship on 30 October 1994, along with Headmaster Igor Karkaroff and his fellow students, including the famous Quidditch Seeker, Viktor Krum. His name was one of the few Durmstrang students mentioned by name when Albus Dumbledore read from a list of the delegates in the Great Hall. During the Welcoming Feast, Harry Potter observed Poliakoff from the Gryffindor table. He noted that Poliakoff had spilled some of his goulash down the front of his robes, an act of messiness that seemed to earn a disapproving look from the fastidious Igor Karkaroff. As a student of eligible age, Poliakoff presumably put his name into the Goblet of Fire in the hope of being chosen as the Durmstrang Champion, though the honor ultimately went to Viktor Krum. He remained at Hogwarts with the rest of his delegation for the duration of the school year, returning to Durmstrang after the conclusion of the Triwizard Tournament.
The novels provide no description of Poliakoff's physical appearance. The only insight into his character is the observation that he was a messy eater, having spilled food on his robes during the Welcoming Feast. This suggests a possible lack of refinement or carelessness, which stood in contrast to the stern and image-conscious demeanor of his Headmaster, Igor Karkaroff.
Poliakoff's specific magical abilities are unknown. However, as a student selected to be part of the Durmstrang delegation and being of age to enter the Triwizard Tournament (at least seventeen years old), he was likely a competent and well-trained wizard, particularly in the Dark Arts, for which Durmstrang Institute had a known reputation.
Poliakoff (Поляков) is a common Russian and Bulgarian surname. It is a patronymic derived from the name Polyak, which means “Pole” (a person from Poland). This Slavic origin is consistent with the general understanding of Durmstrang Institute's location being in Northern or Eastern Europe.
In the film adaptation of Harry Potter and the Goblet of Fire, the character of Poliakoff is played by actor Petar Kyuchukov. He is a background character with no lines. (film)