Just as the Warriors of the Light had to defend their world from becoming engulfed by darkness, the Warriors of the Dark were called to defend their own world from being swallowed by the light many years ago.
After each battle, one of the Warriors of the Dark tells the Warriors of the Light important information for the upcoming battle with the Cloud of Darkness. Before the final battle, the Warriors of the Dark sacrifice themselves so that the Warriors of the Light can save their own world.
The Warriors of Darkness are a group of characters introduced in the post-Heavensward main scenario, serving under Elidibus to stop the Warrior of Light to restore the balance of Light and Dark. The group consists of five individuals: Arbert, Blanhaerz, J'rhoomale, Naillebert, and Lamimi. Their appearances are based on the Midlander Hyur "Meteor Survivor" and his allies from the game's promotional material, while their jobs reference several classes originating from Final Fantasy III. The Warriors of Darkness originally hailed from the First, a reflection of the Source that faced calamity under the Flood of Light due to their actions. Their roles are expanded in the main scenario of Shadowbringers, when the Warrior of Light traveled to the First to prevent the Flood of Light from causing an Eighth Umbral Calamity.
Four of the eight main characters of the game are the Warriors of Darkness: Nacht, Diana, Glaive, and Alba.
At the beginning of their adventure, the Warriors of Darkness are chosen by the Crystal of Lux and blessed with its power, as are four Warriors of Light. During their journey, the Warriors of Darkness find five crystal shards which bless them with the Ranger, Dark Knight, Dancer, Ninja, and Magus Jobs. Both groups of Warriors fight to protect and restore the world.