The Abyss Watchers are a legion of undead united by the soul of the blood of the wolf who took on Artorias' legacy of fighting the abyss. After the Abyss Watchers first relinked the flame, their duty was complete and they became hollow. In their slumber the abyss creeped into them, but they didn't forget their primary object; vanquish the abyss. When they are first encountered they are fighting amongst themselves, due to being tainted by the abyss. However since they are undead, they are in an endless cycle of slaying eachother.
They are the first lord of cinder the ashen one encounters in Dark Souls III. They wear a leather armor with a pointed helmet, and wield a greatsword with a dagger in their offhand. Partially through the fight with the ashen one their weapons are infused with fire, strengthening the power of their attacks.