One of the four 'Coffin Knights' The four knights released from the coffins that Pazuzu attempted to keep hidden throughout Aegis of Uruk. Without Pazuzu, they have awakened and now roam the Tower without a master, attacking various climbers as they see fit. Gremica reveals that they are magical machines, created from the Dark Armour formerly used by the Sumar Empire (Red Knight, Blue Knight, Mirror Knight, and Hyper Knight) and their individual characteristics likely carried over. Henaro's motivation for climbing the tower is to recover the four knights by the orders of Amina and protect the king's shadow. (Source: Wikipedia)
Suguha is Kazuto's adoptive sister in the real world, although later revealed to be his cousin. She is an accomplished kendo practitioner, having practiced for 8 years, following her grandfather's wishes. In ALO her avatar name is Leafa. Suguha originally disliked VRMMO games for it hid peoples' nature and reality, as it did with Kazuto. She took up ALO in order to understand Kazuto better when he was trapped in SAO. She won the Sylph tournament, earning the title as the strongest Sylph before the events of the Fairy Dance Arc. She learned how to play ALO from her classmate, Nagata Shinichi. Suguha has become very good at ALO, because of the many years she has practiced kendo and the skills learned there were very effective for fights in ALO. She enjoys flying in the game so much that Recon even nicknamed her as "Speed Holic."
A beta tester that appears in the third story of Volume 8. He teams up with Kirito to complete a quest.
One of founders of Rulid Village, as well as the Knight Leader of the Integrity Knights, and the oldest Integrity Knight in existence. Bercouli's weapon of choice is the Time Piercing Sword.
A friendly player that meets Kirito at the start of the game and quickly befriends and learns from him. He and Kirito later separate because he has friends who were also new to the game so he couldn't leave them. He survives for the past two years and managed to protect his friends the whole time, something Kirito regretted not doing. He is a katana user and the leader of the small guild Fuurinkazan who participates in the boss battles. As one of the few people close to Kirito, he always keeps him in check and wants Kirito to survive the game. He chose the Salamader race in Alfheim Online. In the side story Caliber, he fell in love at first sight with the girl on the cage named Freyja and agreed that he will help her find her tribe's treasure which is a hammer, though the decision still remains to be a team's decision. The team said yes on Caliber and it turned out that the girl they saved was Thor. It was revealed that Thor disguised as a beautiful girl to get close to Giant King Þrym and retrieve his hammer. Thor defeated Giant King Þrym and that stopped the medallion from being corrupted and ending the quest.
He is trapped in the dungeon under the Black Iron Castle by a faction leader named Kibaou. He is later rescued by Kirito and Asuna in during the Morning Dew Girl arc events after he was thrown into a hidden dungeon. (Source: SAO Wiki)
Rosalia is the leader of the orange guild Titan's Hand, she was caught by Kirito and sent to the prison managed by The Army. As the leader of the guild, and in order to maintain her "green" status, she looks for victims and lures the players to a place where the other members of the guild attack and loot the player, while she maintains her «green cursor» to avoid suspicion. (Source: SAO Wiki)