The Death Guard in the Warhammer 40k universe are a Chaos Space Marine Legion devoted to Nurgle, the Chaos God of decay and pestilence, known for their resilience, endurance, and the ability to endure horrific plagues that would destroy lesser beings. Once loyal to the Emperor, they turned to Chaos during the Horus Heresy, becoming harbingers of death and corruption, spreading Nurgle's foul diseases across the galaxy.