Space Hulks are the galaxy's floating tombs, colossal agglomerations of derelict starships, shattered asteroids, and drowned wreckage fused into single monstrous masses by the mad tides of the warp. Some are the size of small moons, their interiors a lightless labyrinth of buckled corridors, flooded reactor-halls, and chambers that have not known warmth or air for ten thousand years. They drift without purpose, appearing and vanishing from the immaterium at the warp's cruel whim.
Yet they are seldom empty. Genestealer Cults broodlings slumber in the dark, waiting with patient hunger for prey to breach the hull, while feral Orks infest others in howling, ramshackle multitudes, and the taint of Chaos festers in the deepest holds where daemons gnaw at reality's edge. To board a hulk is to enter a killing-ground where every shadow may hide a rending claw.
The Imperium covets them for the archeotech and lost relics buried in their bowels, and Terminator squads are sent to purge them chamber by bloody chamber. Many such boarding parties are never seen again. When a hulk drifts too near an inhabited world, the ork tide it carries can drown a planet in green-skinned savagery. They are horror made vessel, and the void is full of them.