Leonhart von Schroider (レオンハルト・フォン・シュレイダー, Reonharuto fon Shureidā), also known as Leon von Schroeder in the English dub, is an anime-only character who appears in the KC Grand Prix arc. He is the younger brother of Siegfried von Schroider, and he uses the alias Leon Wilson when he duels.
As a child, Leonhart was neglected by his parents, who chose to focus on grooming Siegfried to take on the company. He was forbidden from seeing his brother, as his parents felt he was a distraction to Siegfried, and so instead he passed the time by reading fairy tales. Along the line he became a fan of Duel Monsters as well, and he assembled a deck full of fairy tale-themed cards that Pegasus J. Crawford had made for him. Using the name "Leon Wilson," he gained fame as a duelist and is recognized when he enters Kaiba Corporation's tournament.
Though he participates in the tournament to help his brother, he hopes to duel Yuugi Mutou, whom he admires. Leonhart started looking up to Yuugi after the latter was victorious in Duelist Kingdom, and he has watched all of Yuugi's public duels. During the tournament, Leonhart defeats several duelists, including Rebecca Hopkins, and advances to the finals, where he will duel Siegfried. He is declared the winner by default when Seto Kaiba interrupts the duel and disqualifies Siegfried for entering under a false name. Leonhart is then scheduled to duel against Yuugi next, but before the duel begins, Siegfried manipulates Leonhart into helping him with his revenge against Kaiba by giving him a virus-infected card.
Once Leonhart plays it, the virus activates and infects KaibaCorp's computer systems, causing Leonhart to realize that his brother was lying to him. He is at first unable to destroy the card, but Yuugi helps him to remove it from play, winning the duel in the process. He then makes up with his brother, who felt guilty for tricking him, and in the end of anime, he and Siegfried are shown making a deal with Pegasus.
The cards in Leonhart's deck were made for him by Pegasus after Leonhart wrote Pegasus letters requesting them. They are all related to the fairy tales that Leonhart loved reading when he was a child.