An Obliterator is a Chaos Space Marine, often a Tech Marine or with existing bionics who is believed to have been affected by a so-called "technovirus", a daemonic virus that transformed these once-loyal servants of the Imperium into bloodthirsty mutant weapons of Chaos. They are monstrous hybrids of human, daemon and machine. An Obliterator is able to absorb any weapon into its body that is held for too long. These unfortunates can spawn these weapons from their very flesh, and also grow ammunition for them.
Chaos Obliterators are biologically fused to their suits of Power Armour. They tower over their Chaos Space Marine brethren, and they are usually at least as broad as they are tall, dwarfing even the Terminator armoured escorts of their lords. Their flesh is stretched and distorted across an exoskeleton of metal and plasteel, and pistons writhe and churn under their sallow skin. They eat ammunition and drink Promethium, it is said, for whatever energies an Obliterator consumes, he can replicate within himself.
The first Obliterator was created by an imprisoned Daemon Sa'ra'am. Known as various titles such as The Daemon Beneath, The Knife's Edge, and the Laughter of War, Sa'ra'am claims to have been created when the first mortal made a tool with the purpose of taking another life even before the First Murder, Drach'nyen came to be. Since his birth, Sa'ra'am has only grown stronger as weapons have grown and developed. At some point, Sa'ra'am was bound within the Forge World of Sarum, a fate he secretly relishes as it allowed him to remain free of the direct control of the Ruinous Powers.
During the Horus Heresy, Perturabo journeyed to Sarum and met with Sa'ra'am in order to discover the location of Angron. The Daemon eventually revealed the Daemon Primarch's location to be on the world of Delugeand and as a parting gift to Perturabo, possessed the body of the Iron Warrior Volk, creating the very first Obliterator.