|Energy Fields: Rosarius - Refractor field - Displacer field||Armour: Flak - Carapace - Powered - Artificer - Terminator|
Power Armour is worn primarily by the Space Marines, Sisters of Battle, Adeptus Custodes and the Chaos Space Marines. It is a completely enclosed suit of armour, made of thick ceramite plates. The armour would be heavy and cumbersome to wear but for the electrically motivated fibre bundles within the armour that replicate the wearer's movement and enhance his/her strength.[Needs Citation]
Power armour is fully sealed, isolating the wearer from the outside environment and protecting him from gas weapons and harsh atmospheres. It also commonly includes numerous auxiliary systems such as communicators and auto-senses. The backpack contains the main power plant, environmental system and additional stabilisers.[Needs Citation]
Whilst power armour is most commonly associated with the Adeptus Astartes, the Sisters of Battle and many Inquisitors also use powered armour of one sort or another. Typically however these armours may not contain the same strength-enhancing properties or life-support functions of Space Marine power armour, nor do they provide the same amount of protection.[Needs Citation]
Power armour has been in use since before the Age of the Imperium, from the techno-barbarians of Earth to the original Space Marines created by the Emperor. Over the history of the Imperium, power armour has developed into many different forms. Need, circumstances and recovery of new materials and technology has shaped the armour's evolution.[Needs Citation]
Space Marine Power Armour
Space Marine Power Armour is an extraordinarily sophisticated defensive system which combines huge resistance to physical damage with a sensory array and sealed environment which protects its wearer from the ravages of the void and alien atmospheres. Integrated with the armour are networks of electro-motivated fibre bundles which mimic and augment the muscular strength of the wearer. The true genius of the design, however, lies in its close integration with the already superhuman physiology, senses and reflexes of the Space Marine within. Working in concert, armour and Astartes together become a weapon without equal.
Each suit of Space Marine Power Armour is a work of supreme artisanship, and although it may be one of many, each is a unique artifact whose spirit and history is of deep spiritual significance to both the Chapter to which it belongs and the Space Marine who wears it.
There are numerous different Marks of Power Armour, most of which date back in terms of design and application many thousands of years ago to the time of the Great Crusade and the Horus Heresy. Each has its own lore and genesis in place and time. Even in the 41st Millennium some intact suits from this near-mythical age survive in active service as war-relics of the Space Marines. Countless others have been produced or reacquired since, and different Chapters often have entirely different panoplies they can call upon to armour their forces. It is also far from uncommon for more recently fashioned armour to incorporate slivers or whole components from far older suits as revered connections to the past.
Space Marines go through an arduous process where they receive various implants culminating with the implantation of the Black Carapace, which allows the Marine a direct and instinctual interface with the armour, making it in effect a second skin. The advanced systems of Space Marine power armour also monitor the Marine's biological functions, feeding the medical information to the Marine.[Needs Citation]
Mark 1 "Thunder Armour"
Mark I plate was developed by the techno-barbarian factions that dominated Terra prior to the Emperor's ascendancy. When the Emperor began his conquest of Earth, the "Thunder Warriors", the proto-Space Marines which formed part of his retinue, were armoured in the same way as the soldiers of the other warlords. A thunderbolt and lightning symbol was displayed on the breastplate of warriors loyal to the Emperor - this was the personal badge of the Emperor in those days, predating the Imperial Aquila which only became the symbol of the Imperium much later. The emblem gives the suit its common name – "Thunder Armour."
Thunder Armour was not an enclosing suit and offered no life support functions, being unnecessary while the fighting was confined to Terra and the similar environments of Luna and Mars. This early armour was produced on a completely local basis and as such individual suits varied heavily and their exact designs were often a matter of personal taste.
The main part of the armour is the massive powered torso which encloses the chest and arms. Coiled energy cables beneath the armour plating transmit power from the power pack on the back to the arms, greatly increasing physical strength by a factor of between 3 and 4 times. Since fighting on Terra during this period was primarily close-quarters, the strength of a warrior's chest and arms was of paramount importance. The legs of this armour Mark are typically not power-armoured at all, but are enclosed in tough padded breeches. The best-equipped warriors sometimes wore armoured greaves and armoured boots, and such additional protection was common amongst the Thunder Warriors.
As with all powered armour, the power supply is contained with a notably bulky back-mounted unit, most of which is taken up by cooling systems designed to prevent the entire armour design from overheating.
This ancient style of armour is noticeably noisier than later Marks. 
Mark 2 "Crusade Armour"
After the conquest of the main planets of the Sol system, the factories on Mars were set to work constructing a new type of armour for the Emperor's elite Space Marines. This armoured suit is commonly referred to as "Crusade Armour," since it was designed with the planned Great Crusade in mind. It was decided to list this design of power armour as the Mark II, despite it being the first issued to the Space Marine Legions, with the armour of the Thunder Warriors retroactively designated Mark I. It was the first fully enclosed power armour, with life-sustaining capabilities, making it suitable for combat on toxic alien planets and the depths of space.
Crusade Armour is fully plated, and the legs are also power armoured. The plates are arranged into articulated hoops, for increased maneuverability. The chest coils, which were kept on the outside of the armour plating on Mark 1 armour for cooling purposes, have now been placed on the inside of the chest plates, so that they are better protected, thanks to more efficient cooling mechanisms. However, this design could not be copied over to the new powered leg armour, which resulted in exposed cabling on the backs of the lower legs. The backpack is roughly the same size as that on the Mark I armour, but is much more efficient, and also includes extra life support, air recycling and fluid recovery equipment, as well as automated medical devices that have remained a part of Space Marine armour ever since.
The helmet is fitted with automatic sensory devices developed on Mars, which allow the wearer to see and hear as though not wearing a helmet, and, since all information is transmitted to a computer in the helmet before being transmitted directly to the wearer's brain via neural link, it enhances sight and hearing while dampening blinding lights and deafening noises. The wearer is also able to see in the infra-red and ultra-violet spectrums, images can be zoomed in and magnified while noises can be enhanced. The helmet was fixed in a single position, but allowed the occupant to turn his head inside.
Mark II armour is believed by many to still be the most efficient example of power armour design, although with the caveat that the overlapping hooped armour plates are difficult to repair. It can still be found in operational use - in extremely limited numbers - amongst several Space Marine Chapters.
Mark 3 "Iron Armour"
This model dates from the wars of the Great Crusade, waged close to the galactic core. Many of these worlds were the Squat Homeworlds, which were not pleased to find themselves the object of galactic conquest. The Squats' independent and stubborn nature, along with the conditions of the fighting, spurred the creation of this new armour type.[*] This armour was ideal when cover was minimal and combat was a matter of frontal assault. The most visually brutal and imposing of all the widely produced armour marks, the Iron Armour was a heavy, modified Mark II design (itself the first mass-produced Power Armour of the Crusade era). The Iron Armour's structure has augmented frontal defence and incorporates additional ablative plates, and is intended foremost for use in boarding actions, tunnel assaults and void warfare, although it is considerably heavier and more power hungry than its contemporaries. The new helmet design is a heavily armoured model with sloping plates designed to deflect shots to the left and right, and inspired the Mark IV and VI helmet designs.
Mark III was never intended to replace the previous Mark but to act as an optional suit specialised for situations where heavier frontal protection would be advantageous, such as in the close confines of spacecraft and mining complexes. Because of this, no Legion was ever fully equipped with the Mark III. While successful in the conditions it was designed for, the armour is too clumsy and uncomfortable for conventional fighting. It is sometimes worn by ceremonial guards due to its visual brutality, and can also still be found used in close-quarters situations by various Space Marine Chapters.
It is commonly called the Iron Suit or Armorum Ferrum in recognition of its great strength.
Mark 4 "Imperial Maximus Suit"
At the end of the Great Crusade the Space Marines found their armour wearing out. While some Legions chose to continue local production and maintenance, the Adeptus Mechanicus of Mars started to design a new variant for centralised issue, which was to be designated the Mark IV or Imperial Maximus suit.
At the Mark IV stage of the power armour development, Space Marine armour began to take on an appearance recognisable as contemporary power armour, the main change being the abandonment of the separate abutting plates in favour of larger inflexible armour casings incorporating flexible joints. This marginally reduced mobility but was far easier to produce and maintain.
Technical secrets recovered on newly conquered worlds allowed Mars to develop the more efficient armour, improving the quality of protection and reducing the suit's weight at the same time. Improved armouring of the power cables allowed the main arm and chest supply to be safely relocated to the exterior of the armour, while the use of new material reduced the size and number of cables.
The helmet was a completely new design, the basic shape inspired by the sweeping front of the Mark III. In Mark IV and later versions the helmet is no longer fixed, but moves with the wearer's head. This represented the constructors increasing experience with neural connector gear and the new materials which flooded into the Martian workshops as the Crusade progressed.
Mark IV armour was envisioned at the time to be the ultimate and final type of Space Marine armour, able to offer the best protection in a variety of conditions. Many of the Space Marine Legions were entirely or partially re-equipped with it, although the order of which Legions recieved the armour would shortly prove to be of significance. As a result of its widespread production and use prior to and during the Horus Heresy, Mark 4 suits are the most common of the pre-Heresy armour Marks still in service during the 41st Millennium.
Mark 5 "Heresy Armour"
The equipping of the legions was only partially complete when the Horus Heresy broke out. Many of the Legions that had just been fully equipped with Mark IV armour turned against the Imperium while many of the loyal Legions had been deliberately starved of access to it and and remained operating with the older Mark II and Mark III armour. Additionally, even the Legions equipped with Mark IV suits quickly found themselves low on spare parts and unable to manufacture replacement units. With war damage and mobile operations, resupply for damaged equipment was difficult or impossible. Marine artificers and Techmarines had to use old style equipment from older models to keep the legions fighting, as well as salavage from slain enemies and unorthodox inovations of their own.[1,8]
This ad-hoc assemblage of various armour mark segments (including new or unoffical design elements) being created by a multitude of legions resulted in an entirely new mark of armour being 'accidentally' created; these previously non-standard, emergency/stopgap designs were retroactively termed as the Mark V once production of the Mark IV was halted and the design for the subsequent Corvus Armour mark (Mark VI) was finalised. Some form of standardisation across Mark V suits is is notable, despite their apparently random creation and individual varied origins, due to the dissemination of molecular bonding techniques across the legions. These techniques were developed due to battlefield experiece in fighting other Astartes; Astartes plate needed to be proof against their own penetrator weapons, and it was discovered that power armour would benefit from additional reinforcing in this regard. All sorts of improvised additional armour can be seen on Mark V suits, but the most common technique was affix additional layers of armour with the aforementioned molecular bonding studs. This relatively quick and simple technique effectively added another ablative layer to marine armour suits. The extra weight this generated would prove considerable, however, which placed a strain on power supplies. As the addition of extra power generation sources and cabling would just require more armour plating, catching the design in an eternal circle, the wearers of the suit was forced to either deal with the additional weight, or turn up the power output of his backpack but suffer extreme heat output, which not only would prove uncomfortable and even compromising in certain situations,[1,8] and in many cases older, heavy power cabling was used, which created a weak point on the chest
Many Mark V suits ended up featuring an unusual helmet design appropriated from supplies generated by the Tactical Dreadnought Armour program; this spin-off helmet featured similar levels of improved auto-senses as Terminator suits, but was still found to be inferior to those of Mark IV suits. The respirator design used for the Mark V helm was initially codified as the Mantilla-pattern, and saw use as early as late M30.
The Mark V would be the most common armour mark visible during the Horus Heresy, by its nature as a mark resulting directly from the concerns of that galactic civil war. As a result, the Mark V is commonly called the Heresy Suit and is distinguished by the molecular bonding studs often seem on areas such as helmet, shoulder plates and greaves. Few Imperial Space Marines are ever seen in Mark V suits today, as the loyalist Chapters either broke up these suits for spares or purposefully destroyed them after the Heresy was over. In contrast, many Chaos Space Marines still wear Mark V armour by default, either because they still possess their original suits or because they are forced to scavenge equipment.
This power armour carries resonances of the Imperium’s darkest hour and its greatest victory. Battle-Brothers will offer the wearer their respect. However, members of the Inquisition are instinctively suspicious of any connection to the Horus Heresy.
Mark 6 "Corvus Armour"
At the end of production of the Mark IV armour mark a long term research project began to replace the existing power armour. As this remained a theoretical endeavour for some time, it lead to the production of the Corvus Suit as a stopgap measure using a mixture of new and old features.
The Mark VI suit protype design was field-tested by Legionaries of the Raven Guard, whose experiences and comments resulted in improved design features in the finalised armour mark. Mark VI armour offered no better protection-levels than the Mark IV, but incorporated more efficient internal systems where power-routing and auto-sense were concerned. Power systems were given back-up reduncancies with no increase in weight, while both olfactory and auditory sensors were improved. Additionally, the armour featured the best stealth capabilities of all power armour marks so far designed, as well as a new method of compartmentalising components that allowed them to be swapped out with pieces from previous marks with ease. It is the lightest variant of power armour and featured dual technology circuits that allowed the replacement of rare or sophisticated parts with common or basic alternatives. It also included fail-safes such as duplicate power cabling. 
The finalised armour mark was named Corvus Armour in honour of Corvus Corax, Primarch of the Raven Guard, and the first sets of it shipped to the Raven Guard Legion ahead of all other loyalist legions, in recognition not only of their role in the design process, but of the sacrifices made by the Raven Guard in the Drop Site Massacre and their determinaton to rebuild and rejoin the fight against Horus the Great Betrayer.
The Mark VI features clean, sleek lines, due to the routing of power cables under the exterior armour plate (abdominal covering of these was one of the suggestions made by the Raven Guard) and the increased sloping of the helmet design. The left shoulder armour features the tell-tale molecular bonding studs of Mark V armour. The initial suits did indeed use the ablative technique pioneered in Mark V suits, as paucity of supplies during the Heresy meant that some sacrifices still had to be made, even with a new armour design. In later years, the left shoulder was armoured to the same level as the right, but the studs were still affixed in a deliberate continuation of the honoured design that had won the Horus Heresy for the Imperials.
Chaos Space Marines can be seen in this armour despite its association with Imperial Space Marines; they captured a significant quantity of the suits on Mars during the Heresy, as well as Mechanicum production facilities, and were therefore able to produce their own Mark VI suits.
- Note- This armour is sometmes informally referred to as "Beakie Armour" due to the shape of the helmet.
Mark 7 "Aquila (Eagle) Armour"
Mark VII armour, also known as the “Aquila,” “Imperator” or “Eagle” armour, was developed during the Horus Heresy, and remains in use as the most common form of power armour ten thousand years later. It represents the final major development of Mark 6 armour.
While the final battle for Mars was underway, the Imperium realised the planet would eventually be lost. Armour development teams were transferred to Earth to continue, incorporating their latest work into the armour type that would become Mark 7. As Mars fell to Horus, the new armour began reaching the Space Marines on Terra and Luna.
Mark 7's main improvement is the newly designed chest plastron which covers the chest and arm cabling. The chest bears the Imperial Eagle, giving the armour its common name of Armorum Imperator, or Eagle Armour. This mark abandons the studded shoulder armour plate, and replaces the helmet. As Mark 7 is a development of Mark 6, both have a great deal in common, and parts from one mark are readily interchangeable with parts from the other, like the helmet.
Mark 8 "Errant Armour"
The suit itself is a highly modified Mark 7, with additional fixed armour plates on the torso that now enclose all of the suit's cables, which were vulnerable to weapons fire, and a new armoured collar protects the helmet's respirator, and also addressed the vunerability issues of the neck joint, which had been known to act as a "shell-trap", (a round could hit the chest armour and be deflected up into the neck joint). The new collar required a new helmet design, which caused problems for backward compatibility with earlier helmet types.
Mark 8 armor has only seen limited production thus far, and is seen in limited numbers on the battlefields of the 41st millennium. Often, it is worn by veteran Space Marines as a symbol of rank.
Aegis ArmourAegis Armour
Grey Knights wear Aegis Armour, power armour that is incredibly well crafted; anointed and inscribed with prayers and wards, ritually consecrated and psychically charged. The suits are generally based on components from Mark 6, 7 and 8 power armour designs, with a modified helmet design with a tapered, knight-like visor.
Space Wolves Runic Armour
The Space Wolves grant valiant members of their Chapter specially crafted suits of power armour inscribed with runes of protection by the Rune Priests. These provide the wearer with a defence against psychic attacks. This armour is created by the Iron Priests and codified as Mark 12 Lupio pattern.
A number of variant components for Space Marine power armour are known to exist. Although designs and components are subject to variation, especially in the case of artificer armour, more standardised spin-off designs have been developed over the course of the Imperium's history. These include the Sarum and Phonecian pattern helmets (the latter of which was exclusively used by the Emperor's Children), and the Praetor pattern power armour, which was locally produced at Veridia Forge by the Ultramarines in the later years of the Great Crusade.
In addition, a number of Space Marine backpack units have been identified. Although the M.37 design is the current standard issue, other designs such as the Mars pattern (the standard issue for the Mark II and III power armours) are still used to some extent. Additionally, the Anvilus pattern backpack, a Crusade-era Imperial prototype incorporating advanced thruster vents for use in void operations, but at the cost of decreased radiation shielding, remains a mainstay of the Chaos Space Marine Legions in M41.
Adepta Sororitas Power Armour
The Adepta Sororitas use a version of power armour designed for the human shape and size, known as Sororitas Power Armour. Sororitas Power Armour is the only enduring legacy of the reign of Goge Vandire, who commissioned the armour for his Brides of the Emperor, where today it serves the Sisters of Battle. Crafted by the forges of Mars, Sororitas Power Armour is relatively lighter than most suits, providing excellent protection and increased strength at negligible loss to the user's mobility and agility. It uses the same power source as the Astartes, and thus will effectively last forever if properly maintained and undamaged.
Though Sororitas Power Armour provides the same level of protection as suits worn by the Space Marines, the lack of a Black Carapace means the Battle Sister cannot fully interface with the armour and so lacks the same strength enhancement and other advanced life-support features found in Astartes power armour. Still, Sororitas Power Armour does improve the user's strength and allows them to better handle heavy weapons more easily.
The 'Sabbat' Pattern Sororitas Helm has been a standard part of this power armour since the mid-38th Millennium. In addition to a comm-link and rebreather unit for limited operation in a total vacuum, the helmet includes full-spectrum filtering and psycho-oculal buffering to assist the (less physically durable) human mind from being rendered insensible by battlefield conditions. For the Battle Sisters of the Calixis Sector, this helm is issued only after they have proven themselves worthy of wearing it.
Imperial Power Armour
Power armour is also favored for use by agents of the Inquisition and those individuals wealthy enough to afford one, such as Rogue Traders. These suits of armour enhance the user's strength, allow for operation in hostile environments, and include auxiliary systems such as vox-links and auto-senses. Like the Adepta Sororitas though, the lack of a Black Carapace means these users cannot fully interface with their power armour and so do not enjoy the same strength enhancements and other advanced support systems typical to Astartes power armour.
Ignatus pattern power armours are all fine examples of Mechanicus artisans. Each of them are individuality crafted only for representatives of the Holy Inquisition. Of course not as durable as Adeptus Astartes power armours, the Ignatus-pattern is far better design than those sold to nobles, rogue traders and other agents of the Imperium. Like every other power armour variant, Ignatus too is made of thick ceramite armour plates and incorporated electro-muscles so the user can even use the power armour in the first place. The optional helmet protects the wearer from toxic gasses and allows the wearer to breathe underwater and even survive in vacuum as long as suit has power. The helmet has photo-visors so the user can see in the dark and an automatically closing visor renders blind-grenades useless against the wearer. It is also possible to use a backpack for the suit which acts as external power-source. With this power-backpack the wearer can use his armour for five continuous days in battle conditions.
*: Because the Squats have been removed from the current canon, their role in the development of Iron Armour is usually replaced with the need for heavy armour in close-quarters boarding actions aboard spaceships.
- 1: White Dwarf 129 (UK), Space Marine Armour by Rick Priestley, reprinted in Warhammer 40,000: Compilation
- 2: Codex: Space Wolves (5th Edition), pg. 61
- 3: Codex: Witch Hunters, [Needs Citation]
- 4: Games Workshop Official Site
- 5: Dark Heresy: Blood of Martyrs, pg. 118
- 6: Deliverance Lost (Novel) by Gav Thorpe, [Needs Citation], pgs. 328-30
- 7: Rogue Trader Rulebook, pg. 139
- 8: Deathwatch: Rites of Battle, pgs. 149-152
- 9: Imperial Armour Volume Ten - The Badab War - Part Two, pgs. 168-169
- 10: The Horus Heresy Book One - Betrayal [Needs Citation]
- 11: Know No Fear by Dan Abnett, Target//Acquisition, [Needs Citation], pg. 20
- 12: Codex: Space Marines (3rd Edition) by Andy Chambers, Jervis Johnson, and Gav Thorpe, pg. 2
- 13: The Horus Heresy Book One - Betrayal pg.22
- 14: Dark Heresy: Ascension pgs. 143-144