Servo-skulls are drone-like robotic devices that appear to be human skulls outfitted with electronic or cybernetic components that utilise embedded anti-gravity field generators to allow them to hover and drift bodiless through the air. They are fashioned from the skulls of loyal Adepts of the Adeptus Terra and other pious Imperial servants to which robotic components and an antigravitic impeller have been added. This is so that they may continue their work for the Emperor of Mankind even after death. To have one's skull chosen to serve as a Servo-skull is a great honour in the Imperium, for it implies one's service in life has been satisfactory enough to warrant continuation beyond death.
Servo-skulls form an important niche in Imperial work, serving as everything from auto-scribes that copy down important conversations and confessions of prisoners, to simple moving torches, hovering about their charge with candles and electric lanterns to illuminate the area. Certain Magi of the Adeptus Mechanicus and high-ranking Imperial officials have special logic engines and Cogitators (computers) that slave Servo-skulls to a particular owner.
Servo-skulls are used throughout all the different Adepta of the Imperium of Man, and each is built to perform a certain task. Some are designed for military roles, and among these some are built with enhanced optical sensors to allow them to fulfill a role as a reconnaissance scout. Servo-skulls are often used by Inquisitors and Inquisitor Lords as non-human assistants referred to as Familiars. In this case they are mentally linked to the Inquisitor through psychic or cybernetic means, allowing him to control them and see and hear through their senses.
- Guardian-Skull - Designed with a somewhat reinforced structure and fitted with a single effcient weapon system and targeting selection programs, guardian-skulls (also known as gun-skulls and combat-skulls depending on their armament) are uncommon but prestigious and effective bodyguard devices. Their small size, tireless vigilance, and ability to hover in the shadows silently make them surprisingly discreet and effective servants.
- Servo-Hunter - A variant servo-skull often utilised by planetary Enforcer cadres and less well-funded enforcement agencies which do not have access to the meticulously-engineered Cyber-mastiffs or grapplehawks of the Adeptus Arbites. These agents utilise shoddily constructed cyber-familiars to carry out similar duties. Servo-hunter's are classic examples: these small, comparatively simplistic familiars are an inferior local variant upon a servo-skull, tasked with the exploration of a fixed location, and the identification of any potential targets within. Popular amongst the Enforcers of the worlds of the Malfi sub-sector, servo-hunters are traditionally encased within the skulls of faithful hunting hounds, as the deceased animal's spirit is said to ensure that the drone’s rudimentary logic-engine remains loyal and fierce. A servo-hunter, when activated and released, will float silently on tiny lift-motor suspensors and begin to search a nominated area for any targets which match preset parameters (usually human-sized heat sources). When these are located, it will usually provide its handler with some audible alarm, and will remain alongside the target, sounding the alarm, until deactivated. The servo-hunter can also be used to patrol an area for intruders, or simply alert the controller if anyone approaches. A servo-hunter is a primitive servo-skull used by enforcers and bounty hunters. It only has a single function, and that is to search a given location until it finds a target; at this point it will signal its master. It will continue to hover alongside the located target, signalling, until ordered to stop.
- Harrier-Skull - Mockingly known as "grapple-mice" by the underhive gangers of Scintilla, Landunder, and several other Calixian Hives, Harrier-Skulls are slowly spreading across the Calixis Sector. The modified servo-skulls actually have nothing to do with mice, but earned the nickname because of their unique purpose—serving as Grapple-hawk decoys. Certain reclaimators can spend a great deal of Thrones to learn how to re-program a salvaged servo-skull's primitive cogitator-engine with a very specific series of evasion patterns. Something about the evasion patterns triggers a Grapplehawk's threat/targeting routines, sending the servitors diving after the nimble Harrier-Skulls instead of their actual targets. As their popularity increases, increasingly frustrated Arbitrators make a point of targeting any Harrier-Skulls first in a suppression raid.
- Monotask-Skull - The most common form of servo-skull encountered, monotask-skulls are designed and equipped to offer assistance with a particular task, and most are fitted with a basic set of extendable manipulator pincers and whatever esle by way of gear their duty requires.
- Codex: Witch Hunters (3rd Edition), pp. 14, 22
- Dark Heresy: The Inquisitor's Handbook (RPG), pp. 144, 145
- Dark Heresy: Book of Judgement (RPG), pg. 76
- Rogue Trader: Core Rulebook (RPG), pp. 147, 375
- Warhammer 40,000: Dawn of War (PC Game)
- Forge World - Servo-Skulls
- Forge World - Grey Knights -- Servo-Skulls