Tactical Dreadnought Armour, more commonly known as Terminator Armour was developed for close-quarters fighting, where staying power was more important than maneuverability. The technology was originally developed to enable maintenance crews of space ships to operate in hard vacuum or in other adverse conditions. It was re-designed during the Great Crusade to replace Power Armour, but was relegated to its current role due to a lack of maneuverability.
It is manufactured from a ceramite plasteel alloy as an exoskeleton with servo assisted interfaces with the users own neurological and muscular systems to enhance movement. It is the heaviest armor in any Imperial arsenal, is able to withstand tremendous punishment, and serves as a solid heavy-weapons platform in open-field combat. The First Company of most Space Marine Chapters uses Terminator armor extensively, and only those Marines who earn the crux terminatus are permitted to wear it.
Less frequently, high ranking members of the Inquisition have been known to wear Terminator armor. Notably, members of the Ordo Malleus can be seen wearing them. However, due to not being able to interface with the armor, inquisitors find the armor to be more cumbersome than a Space Marine would.