The Carnifex is a monstrous Tyranid organism that is used as a living tank by the hive fleets. It is armed with the most advanced Tyranid Bio-Weapons and is used primarily as a shock trooper to carry out starship boarding actions, frontal shock assaults on entrenched positions and for besieging fortified locations or enemy armour formations. As Tyranids are constantly evolving their forces, many different species of the Carnifex exist. However, all Carnifex share some common characteristics: they are very large creatures, standing significantly larger than a man; they have a thick carapace, which provides excellent protection from damage, and they frequently use some of the bio-weaponry utilized by the Tyranids. Any Carnifex can be mutated to possess Thornback Armour, a Barbed Strangler, Spore Cysts, a Venom Cannon, or to project burning Bio-Plasma.
There are four variants of original Carnifex. These are:
- Thornback - The thornback bears genetic enhancements that resemble large spikes or thorns, and are commonly used to breach enemy lines.
- Screamer-Killer - Screamer-Killers are easily identified by the piercing shriek that got it the "Screamer" part of its name. Unfortunately, this is almost always followed by a blast of Bio-Plasma.
- Bile Beast - The Bile Beast spews acidic fluids onto its foes before attacking in close combat using its huge crab-like claws.
- Stone-Crusher- The Stone-Crusher is a siege variant of the carnifex. Armed with huge crushing claws, capable of tearing down the thickest walls, a massive scything tail and battering rams, used for crashing into enemy ranks and fortresses.