A reimagining of Warhammer 40k Terminator Armor.
In Warhammer 40.000 universe, the Terminator Armor (aka. Tactical Dreadnought) is a kind of heavy, powerful exoskeleton/armor, a lighter and smaller version of the powerful and enormous walker known as Dreadnought, made for close combat and destruction of violent and dangerous threats.
The last Terminator armors were fabricated in the Dark Age of Technology and just before the Horus Heresy, making them precious artifacts with thousands of years each.
I never really liked how W40k Terminator armor looks like. It was just a regular power armor with a hunchback and a helmet that looks like a ugly dog face, just the Aegis Armors (from the Gray Knights) were cool looking.
I based my design more in the Ironmonger armor from Iron Man, more like a mecha, with mechanical legs and arms to stand powerful recoil from auto-canons and missile launchers without need to brace for impact. The pilot ride inside the Terminator torso, sitting and controlling the movement with pedals and joysticks.
Adeptus Astartes could control the Terminator overall movement linking their Black Carapace to the mecha Machine Spirit, leaving the hands free for other important tasks, like putting 40k iPods in the ears, eating snacks or pleasing Slaanesh with an issue of PlayAstartes (in case of Chaos Space Marines, and you know what I mean...). In combat the Astartes could concentrate in more elaborate movements, like reloading guns, operating mechanisms and opening doors with keys or keycards (try opening a simple lock with one of these... [link]
it's too damn difficult!)
As I read in the Warhammer 40k Wiki, it's possible for a normal human to ride a Terminator Armor, but they would find it very difficult and bulky. Some Ordo Malleus Inquisitors wear them like the Gray Knights, but not as good as an Astartes would wear them...