A Dead World is an Imperial planetological classification applied to worlds which are utterly devoid of an ecosystem, atmosphere, or any form of native life, much like the Earth’s Moon, Luna. A Dead World is, of course, not suitable for human habitation without undergoing massive terraforming operations. While it is possible that the Imperium might establish scientific Research Stations on Dead Worlds, there is no other native population. Many of these worlds have always been dead, but some were reduced to their barren state by external events such as the destruction of their preexisting civilisations in some form of global castrophe like a thermonuclear war, a Tyranid incursion or even an Exterminatus carried out by the Imperium itself. Necrons often inhabit Dead Worlds, however, having chosen them millions of years ago to become the Tomb Worlds upon which they went into hibernation until sentient life had repopulated the galaxy.