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The Bloody Baron was a former student at Hogwarts School of Witchcraft and Wizardry back during the founders’ time. He was one of the first Slytherins at the school. The Baron lived from around 982 C.E. to sometime in the early eleventh century. During his years at Hogwarts, he fell in love with Helena Ravenclaw. However, this love was unrequited. Years later, he was asked by Rowena Ravenclaw to go find Helena, who had run off with her diadem. The Bloody Baron tracked her down to a forest in Albania. He begged her to come back with him, yet she refused. The Baron had always been known to have a quick temper and in a fit of rage, he killed the woman he was in love with. Stricken with grief, the Baron took the murder weapon and killed himself. Today, he and Helena both reside in Hogwarts Castle as house ghosts of their respective former houses. To this day, the Baron and Helena do not interact in their ghostly or artistic forms. This is probably due to Helena refusing to talk with her murderer and the Baron being ashamed for his actions in the past.

As a ghost, the Bloody Baron is covered in the blood of Helena Ravenclaw, now known as the Grey Lady. Besides the Baron and the Grey Lady, none of the other ghosts know why he is covered in blood. He also carries chains as a sign of penance and shows to be very remorseful of his actions. Nearly Headless Nick has once stated that groaning and clanking around is one of the Baron's favorite pastimes. The Bloody Baron and Albus Dumbledore are also the two people who can control Peeves. The Baron finds the poltergeist's actions intolerable to the point that he made a decision at the Hogwarts ghost gathering to prevent Peeves from attending the start of term banquet in 1994.

There is a tetraptych of the Bloody Baron, four paintings arranged together to be displayed as a singular painting, hung in the Hogwarts dungeons near the Potions classroom. . The Bloody Baron often haunted this area of the castle when the tetraptych was first hung in 1995. The portrait depicts the Baron elegantly posed in red robes, pulling out his sword from its scabbard.