Skeleton Knight

The Skeleton Knight is a being from an urban legend and the main antagonist within the Yu-Gi-Oh! 5D's manga.

When a duelist claps their cards together at sunset, he is said to appear and give them rare cards.

Biography
After Sect Injuin lost to Yusei Fudo in a factory in Satellite, he held his cards up to the sunset, clasped them together and prayed for cards to help him beat Yusei.

The Skeleton Knight appeared on an altar which had not been there before and took Sect captive. Yusei demanded that he give Sect back, but the skeleton challenged Yusei to a Duel. He is defeated when Yusei breaks the pipe he was running along, causing him to get disqualified for stopping. After losing, he starts to disappear, but asks Yusei his name before totally vanishing.

While Sect is in the hospital, the Skeleton Knight appears to him in a dream. According to the ancient edicts, the knight says that he shall grant Sect's wish. When Sect wakes-up, he finds himself holding a card: A level 8 monster card, named Demon King Dragon Beelze.

The Skeleton Knight later appears behind Yusei whilst he is turbo dueling against Hunter Pace, as one of his servants, Sect was currently being infected by one of the Skeleton Knight's dark cards, which Yusei along with the other Signers could feel.

During Sect and Jack Atlas' duel, the Skeleton Knight interrupts the duel by bursting out of the ocean on his altar and salvaging Sect before he lost to Jack. It then reveals that he and Sect are involved within an evil, dark cult known as the Skeleton Knight's Crusade, which consist of several duelists who wished for cards from the Skeleton Knight. These members all follow his commands and consider the Signers their enemies. He then disappears with Sect, leaving Yusei and Jack shocked at the events that just occured.

Deck
The Skeleton Knight uses a "Hellfire" Deck consisting of several Zombie-type monsters, and his personal Duel Dragon Underworld Dragon Dragonecro, along with effects which revive and use the opponents monsters as his own.