Power Armor

Possibly the most prominent feature of the Space Marines is their power armour, a suit of ceramite plates with armoured fibre bundles and servos that replicate the wearer's movements and enhances a Space Marine's already superhuman strength, as well as allows them to easily withstand fire that could kill a normal human. The suit is coupled to the nervous system of the Space Marines via the Black Carapace.

There are eight known versions of power armour in use by the Space Marines:

Mk1 Thunder Pattern Power Armour; the first Power Armour created for the Space Marines. It was developed from the armour worn by the techno-barbarians that plagued Holy Terra near the end of the Age of Strife. It was used during the Emperor’s campaign to retake and unite the Terran solar system before the Great Crusade. It was by no means unique to the first Space Marines - in fact, the techno-barbarian warriors the Emperor fought during the conquest of Terra wore it too, and the Emperor's forces were wearing it even before the first Space Marines were developed. However, because it was designed with Earth-fighting in mind, it is not fully enclosed, with no means to support the wearer in a vacuum. Only the upper body is powered, due in part to the fact that during the Conquest of Terra, ranged weapons were difficult to make due to technological constraints, and so a warrior's upper-body strength was his most important asset. It takes its name from the thunder symbol the Emperor had before adopting the double headed eagle.

Mk2 Crusade Pattern Power Armour; was developed towards the end of the Age of Strife and was used during the dawn of the Imperium during the Emperor’s Great Crusade to retake the lost worlds of man. It was designed as a fully enclosed suit with life-sustaining systems that now allowed the Space Marines to fight in deep space and on alien worlds with hostile atmospheres or environments. The armor was made up of circular armour rings fitted under and over each other, making this armour relatively tedious to repair (see also Lorica segmentata). These precious relics are still used during ceremonial procedures by some chapters and given to champions as battle armour in others. These suits are also referred to as Crusader Armour.

Mk3 Iron Pattern Power Armour; it was soon realized that fighting in the tight corridors of spaceships was very dangerous. The Iron suit was designed to give greater protection to the Marines. The frontal armour was much thicker (thereby giving greater protection), but the rear armour was thinner to compensate. The wedge-shaped helmet (designed to deflect incoming fire) formed the basis of the distinctive Corvus beak helmet.

Mk4 Maximus Pattern Power Armour; this armour was to be the replacement for the old Mk2 armour of the Great Crusade; it was the first armor to incorporate many components used in modern armour. However, it was made from rare alien materials, and when the Horus Heresy broke out soon after it was issued, it was discovered that most chapters cut off from supplies could not find the materials needed to make it or repair it, and they often suffered irreparable damage by relatively minor battles.

Mk5 Heresy Pattern Power Armour; this armour was developed as a solution to the supply problems of the Horus Heresy. It was easily made from the most basic of materials, and it was easy to maintain. Almost all soldiers used spikes to hold the armour layers together, making the studs shown universally on all examples of this armour. In time, it became traditional for the studs to be found on the head, lower legs, and left shoulderpad of the armour. Due to the sub-standard materials used in the construction of this armor variant, it had a tendency to over-heat quickly, and many marines had to endure sub-standard performance by turning down the power output of their backpack to prevent intolerable heat build-ups.

Mk6 Corvus Pattern Power Armour; this classic variant can be traced back to the time of the Horus Heresy and is still commonly used in contemporary Chapters. It is characterized by the beak-like muzzle on the helmet and a studded Auto-reactive shoulder plate on the left shoulder of the armour. The beak or muzzle led fans to nickname this variant "Womble armour" or "Beakie armor", and a dictionary of the Orkish language in the 2nd Edition Ork Codex listed Marines as "beakies". This was the style of the first Space Marine models released by GW and did not get its Mk6 terminology until after models with the Mark 7 styling were released. Models with this style were not part of new releases until the launch of the next range of 25 mm plastic models.

Mk7 Aquila Pattern Power Armour (also known as Imperator armour) is the contemporary variant most commonly used by the Space Marine Chapters. Characterized by the grim looking Vox caster (external vocalizer) on the faceplate, and the plastron displaying the Imperialis (a winged skull), which has given the armor different names such as Armorum Impetor or Eagle Armour ("Aquila" being the name of the two-headed eagle which symbolizes the Imperium).

Mk8 Errant Pattern Power Armour; this is an update to the Aquila pattern armour, and is distinguished by a raised collar at the front, and armoured plating for the torso cables. Full versions of this armour are almost never seen; however, it is common to find parts of it being used by officers and veterans on the battlefield.

One design feature of Mks 6 through to 8 is their adaptability; it is fairly common within most Space Marine chapters to see a suit combining parts originally created for three or four suits, salvaged from dead brothers on the battlefield. Mk 7 armour, in particular, was created with this simple modularity in mind.

The Sisters of Battle and several high-ranking members of the Inquisition also use Power Armour, but they are not directly linked to their suits in the way Space Marines are, which decreases the armor's effectiveness.