Character: Oberon

Nobuyuki Sugou is the main antagonist of the Alfheim Online arc. He is the one responsible for keeping 300 Nerve Gear victims, including Asuna, prisoner even after SAO had ended. He did this by transferring them all into ALO for experiments on human subjugation via fulldive technology. He also attempts to take over RCT Progress Inc. by marrying Asuna while she is unconscious. He displays a perverse interest in consummating this marriage while Asuna is still comatose. In ALO, he takes on the identity of Oberon the Fairy King and makes Asuna his queen, Titania. When he and Kirito finally meet, he flaunts his GM status as well as the results of his research by causing Kirito immense amounts of pain after increasing Kirito's pain limit and impaling him. He is defeated when the "Ghost Program" of Akihiko Kayaba reminded Kirito how he was defeated by Kirito's determination, before aiding him in overcoming Nobuyuki's GM status. All 300 victims are released from ALO, but Nobuyuki makes another attempt to attack Kirito while he is making his way to Asuna in the real world. However, he is once again subdued by Kirito, who puts the unarmed combat skills he had learned in SAO to useful effect. Nobuyuki is then arrested and charged for his crimes.

Source: Wiki