Argus the Exterminator is the sixth boss that guards Floor 96 in Castle Incrad. Argus is another of the "Titan Ten" bosses who's power is not able to be registered by the Cardinal System.
Argus is by far the most intimidating and dangerous Titan Ten boss ever faced in SAO. His immense size is meant to strike extreme fear and paranoia. The skeletal appearance is similar to The Skull Reaper, but Argus is far stronger.