Commander Skeleton are the commanders of the Dimension of Death's skeleton guard.
Background[]
These guys are big and bad. When one sees one of these guys, they’re in for a battle. Their heavy armor gives them good protection and their massive size and heavy sword deliver a crushing blow. One must be prepared to use their health items quickly. A potion of shield is not a bad idea either!
They are the skeleton's who were in charge of Lord Azriel's Skeleton forces. They turned on their lord.
One commander guarded the East Tower.
Another commander guarded the Shrine of Azriel's Hammer.
Another commander was just beyond the Gate to Life, it guarded the Bridge of Life with a small contingent of skeletons. He is the Skeleton King the leader of the skeleton guards.
One final commander guarded the way to room with the Chalice of Order within the Temple of the Sun.
Both Door Master and the Key Master of the Realm of the Dead wear similar armor to the Commander Skeletons, but it is unclear if they share a similar role in their respective land.
Behind the scenes[]
The KQ8 Hintbook refers to them as 'Commander Skeletons'.
These generally serve as bosses, and there are four in the game.
Technically the tower skeleton looks just a regular skeleton wearing extra armor (though in the official hintbook it is definitely stated to be a Commander Skeleton). It doesn't have the gemstone in its forehead or the roman like armor/skirt, like the regular commander skeletons. However, he has his own textures in the files.
The skeleton commander in the Temple of the Sun and the one guarding the Hammer of Azriel are known as Skelhmr in the debug mode... However the skeletons do not wield a hammer.
Commander Skeletons wear armor similar to that worn by the Door Master and Key Master in KQ6, at least as far as the 'skirt'.