Navigator

The Navigators are the pilots of all large spaceships of the Imperium. Having strong psykic abilities, they are able to navigate the ships through the immaterium, enabeling faster-than-light travel.

Their ability to navigate are depending on the psykic ability contained in their genes, and on the Golden Throne of the Emperor, that act as a psykic beacon in the immaterium.

All navigators are organized in navigator houses, that are extremely rich since they have monopoly on cross-system trade. The houses also control the selective breeding of the navigators, that ensures that the comming generations will retain the gift of navigation.

Since the navigators have been selectively bred since the time of the Emperor, they have evolved into their own race, to the extend that they even have a third eye in their forehead. As they experience a lifetime of contact with the warp, they degenerate further from humans and eventually their form become too bloated to recognize as humanoid. However, the Imperium is entirely dependant upon the services of the navigators, so they are allowed to live and do buisness, despite being mutants.

(Source: Wolfblade)