Heathcliff

Heathcliff is the guild leader of the Knights of the Blood, one of Aincrad's two strongest clearing guilds, and widely regarded as the single most powerful player in Sword Art Online. Wielding a one-handed sword and tower shield in a combination other players consider inefficient, he nonetheless survives boss fights that kill everyone around him, and rumor holds that his hit points have never even dropped into the yellow zone.

Calm, courteous, and something of a mystery even to his own guild, Heathcliff commands deep respect from clearers on the front lines, including Asuna, who serves as his sub-commander. He rarely reveals much about himself, preferring to lead from the front and let his results speak for him.

His true nature is eventually exposed during the climactic duel with Kirito on the 75th Floor: Heathcliff is unmasked as an avatar of the game's own creator, using an administrator account that made him effectively unkillable, until Kirito's victory finally clears the game.