Servo-skull

In all their grimey fashion

A servo-skull is a kind of machine used by the Imperium of Man. They are made from the skull of a deceased Imperial servant with a cogitator, some sensoria, and a hover-drive installed to make it move. What better way to reward an adept of the Administratum for his decades of shuffling around papers that nobody ever reads again than to make his skull into a little flying robot?

Much like the drones used by the Tau Empire, the Imperium puts servo-skulls to many purposes. Some of them are used as pict-recorders and message couriers, others as remote viewers linked to a controlling tech-priest, still others as psychic foci or targeting computers to assist Inquisitors and their retinues. Occasionally they have pistol sized weapons and can be used as assassination tools or a hands-free ranged weapon.

Famous Heads

One particularly "reknowned" Servo-Skull is that of Brother Brantor who was a marksman in the Deathwatch. Somehow rather than getting the honoured rest that he deserved, his head never left the service of the Ordos Xenos, who then fitted it with a stealth anti-grav and a whole range of sensors and auspexes (presumably because a Space Marine's skill might be big enough to fit everything) which makes it/him extremely useful for recon missions and the like. Improbably, the skull is also a better close combatant with an increased weapon skill, which certainly cannot be a carry over of experience, since all brain matter is replaced with cogitators, so obviously the Ordos Xenos still knows how to get access to high-quality artificial intelligence.

Cherubim

One particularly messed-up variant of a servo-skull is the cherub (also called cherubim), which uses a vat-grown baby instead of a skull of a dead servant as the base structure and are therefore have much more in common with your garden variety servitors rather than simple robotic machines.

It sounds like something Slaanesh dreamed up, but apparently it's all the rage for higher-ups in the Ecclesiarchy to have little choirs of the things to sing hymns.

One member of the GW staff went to an extended length in describing where they came from and what various purposes they are suited for. According to the history, they first turned up in M33 to celebrate the ascension of the Emperor to the Golden Throne, where the Adeptus Biologicus released 2000 cherubs into the Throne Chamber (one for each year of his enthronement) where they all flew up into the rafters to sing hymns and remain there still, being maintained by the mechanicum, and presumably shitting on everything just like pigeons do.

Goge Vandire later had them installed EVERYWHERE during the Age of Apostasy, acting as mobile CCTV cameras so he could spy on everyone looking for sedition.