A Sergeant is a large, humanoid Heartless with black skin. It has large hands with yellow claws and wears tattered, black boots with curled toes. It also wears silver bracelets and white knee guards. Its pitch-black head and glowing yellow eyes are visible under its white helmet, which is decorated by a curled antenna and two angular, black spirals. The Heartless emblem is emblazoned on its chest.
The Sergeant's name is a military term referring to the highest rank a non-commissioned officer can hold in most non-naval military forces. This reflects the Sergeant's large size and great strength in comparison to its relatives.
Battling the Sergeant shouldn't be a challenge. Its large size doesn't help it at all in battle, making it rather easy for attacks to connect. While you may wish to attack repeatedly, this is not advised, as the Heartless will counter after a while with a powerful kick. This is the only attack in this boss's arsenal. It will not attack otherwise. Defeat the Sergeant, and it's Mission Complete.