Lightwardens are powerful creatures of primordial Light in Final Fantasy XIV. Introduced in Final Fantasy XIV: Shadowbringers, Lightwardens take command of the Sin Eaters in a surrounding region. Though the Sin Eaters are motivated by only the basest of instincts, such as hunger, even they answer to a hierarchy, and follow the most powerful among, thus giving rise to what the locals of the First dubbed Lightwardens.
Emerging in the First after the Flood of Light was briefly halted, the Lightwardens began taking foothold in Norvrandt, the last land in the First not consumed by the Flood, and began to plague the survivors. Since a Lightwarden's aether could corrupt those who slay them, allowing them to reconstitute themselves, it proved near impossible to destroy them. Despite this, the Crystal Exarch discerned a weakness in the Lightwardens and found a solution in the Blessing of Light. With Hydaelyn's blessing, the Light of a slain Lightwarden could be contained, allowing night and darkness to return to the afflicted region. Just as an insect colony would perish in the absence of its queen, the Sin Eaters would scatter in droves.