Bartemius “Barty” Crouch Jr. was a wizard and a fanatically devoted Death Eater loyal to Lord Voldemort. Despite his brilliance and prestigious family background as the son of Ministry of Magic official Bartemius Crouch Sr., he chose to serve the Dark Lord. His capture and imprisonment for torturing Frank Longbottom and Alice Longbottom led to a complex series of events, culminating in his escape from Azkaban and his pivotal role in the Second Wizarding War. As the primary antagonist in Harry Potter and the Goblet of Fire, Crouch Jr. masterminded the plot to restore Voldemort to a physical body by impersonating the Auror Alastor Moody at Hogwarts and manipulating the Triwizard Tournament.
Born to the influential Bartemius Crouch Sr. and his wife, Barty Crouch Jr. was a highly gifted student at Hogwarts School of Witchcraft and Wizardry, achieving twelve O.W.L.s. After graduating, he joined Lord Voldemort as a Death Eater. Following Voldemort's first downfall, Crouch Jr., along with Bellatrix Lestrange, Rodolphus Lestrange, and Rabastan Lestrange, captured the Aurors Frank Longbottom and Alice Longbottom and tortured them with the Cruciatus Curse in an attempt to learn Voldemort's whereabouts. They were caught and brought to trial before the Council of Magical Law, presided over by Crouch Jr.'s own father. To save his reputation, Crouch Sr. publicly disowned his son and sentenced him to a life sentence in Azkaban.
Crouch Jr.'s dying mother persuaded his father to arrange an escape. During a visit, Mrs. Crouch used Polyjuice Potion to switch places with her son. She died shortly thereafter and was buried outside Azkaban under his name, while the real Crouch Jr. was smuggled home. For over a decade, Crouch Sr. kept his son hidden under an Invisibility Cloak and controlled him with the Imperius Curse. The family's house-elf, Winky, was tasked with caring for him. During the 1994 Quidditch World Cup, which he attended under the Invisibility Cloak, Crouch Jr. managed to fight off his father's Imperius Curse. He stole Harry Potter's wand from his pocket and later used it to cast the Dark Mark into the sky, causing mass panic. This act led his father to dismiss Winky, whom he blamed for the incident.
Acting on information from Bertha Jorkins, Lord Voldemort and Peter Pettigrew traveled to the Crouch home. They overpowered Crouch Sr., placing him under the Imperius Curse, and freed Crouch Jr. He immediately reaffirmed his loyalty to Voldemort, who tasked him with a crucial mission: to ensure Harry Potter would reach the Triwizard Cup, which would be turned into a Portkey to transport Harry to Voldemort. To carry out this plan, Crouch Jr. attacked the renowned Auror Alastor Moody, who was due to teach Defence Against the Dark Arts at Hogwarts. He subdued Moody with the help of Pettigrew and imprisoned him in his own seven-locked magical trunk. Using a constant supply of Polyjuice Potion, Crouch Jr. assumed Moody's identity for the entire school year.
As 'Moody', Crouch Jr. proved to be a surprisingly effective, if unorthodox, teacher. He successfully fooled everyone, including Albus Dumbledore. He manipulated events to ensure Harry's participation and success in the Triwizard Tournament. He put Harry's name into the Goblet of Fire, provided hints for the first task, guided Harry on how to solve the riddle of the golden egg, and arranged for Harry to learn about Gillyweed for the second task. For the final task, he stunned Fleur Delacour and used the Imperius Curse on Viktor Krum to clear a path for Harry to reach the Triwizard Cup. During this time, his father briefly escaped and attempted to warn Dumbledore, but Crouch Jr. murdered him on the Hogwarts grounds, transfigured his body into a bone, and buried it in the Forbidden Forest.
After Harry returned from the graveyard in Little Hangleton, Crouch Jr. brought him to his office, planning to kill him and be hailed as a hero by Voldemort. However, his Polyjuice Potion wore off, and his true identity was exposed by the timely arrival of Dumbledore, Minerva McGonagall, and Severus Snape. Under the influence of the truth potion Veritaserum, he confessed the entire plot. Before he could repeat his testimony to the Wizengamot, the Minister for Magic, Cornelius Fudge, arrived at Hogwarts with a Dementor as a bodyguard. The Dementor administered the Dementor's Kiss to Crouch Jr., sucking out his soul and leaving him in a permanent, vegetative state. This ensured he could not provide evidence of Voldemort's return, allowing Fudge to continue denying the truth.
In his youth, Barty Crouch Jr. was described as a pale boy with straw-colored hair and a face full of freckles. After his time in Azkaban, he became thin and gaunt, appearing much older than his years. Crouch Jr. was highly intelligent, cunning, and a masterful actor, capable of perfectly impersonating Alastor Moody's gruff personality and paranoia for almost a year. His defining trait was his fanatical, obsessive devotion to Lord Voldemort, whom he revered as a father figure. He was deeply resentful of his own father for his coldness and public disownment. He was also exceptionally cruel, arrogant, and ruthless, showing no remorse for torturing the Longbottoms, murdering his own father, or his plot to kill Harry Potter.