Brother Incendia of my Salamander battle force.
A Space Marine Dreadnought is a large, walking tank which carries both powerful guns and lethal close combat weaponry, armoured to withstand all but the most powerful of enemy firepower and often relied on by Space Marine forces to tear an opening in enemy defenses. Each Dreadnought contains a living being, permanently interfaced with the machine through a form of mind impulse unit. Dreadnoughts are surprisingly agile, able to walk and balance with the ease of a living creature.
The pilots within Dreadnoughts are Marines who have suffered mortal wounds in battle, maimed and crippled beyond recovery - instead of being mercifully killed, the greatest heroes are instead given what is considered an honour of continuing to serve the Emperor past their normal life. Once interred within the Dreadnought, the Marine cannot leave the metal womb and is destined for a life of endless battle until destroyed. Some are so ancient their memories may extend back to the founding of their chapter and its earliest history. For this reason they are revered not just as powerful warriors but also as ageless forebears and living embodiments of battles fought long ago. If a dreadnought is destroyed, the Space Marines will fight to retrieve the armoured shell so that the occupant can be returned to the chapter's mausoleum for the long deserved final rest.5
Dreadnought machines themselves are ancient, the oldest dating back tens of thousands of years to the Age of Strife. Because the art of constructing them has been almost lost, Dreadnoughts are revered as rare machines.
Dreadnoughts are armoured with ceramite and adamantium, their muscles are formed of electro-fibre bundles and magna-coils. They are usually armed with weapons to suit a particular role, such as destroying other heavy armoured vehicles.
Although a Dreadnought can be damaged and disabled, it can survive unless the actual armoured tomb containing the occupant's form is destroyed. When not fighting, the Chapter's Techmarines will allow the fallen heroes to sleep away the centuries, until once more they are called to battle.