The Imperium being the Imperium, new suits of Terminator armor are produced very slowly these days by Forge Worlds due to their high cost and the fact that the Adeptus Mechanicus continues to go on its Alzheimer's streak by constantly forgetting how to make anything good besides Titans. In spite of their incredible rarity, Terminators are frequently deployed to Space Hulks since it's the only level of protection that can withstand the intense radiation found within many hulks. Because most chapters generally have far fewer Terminator suits than standard power armor suits, Terminator armor is generally reserved for the veterans of a Chapter's first company (though codex-deviant chapters will have their own rules on who gets termie armor). Terminator armor or 'Tactical Dreadnought Armor' is a holy relic of a Space Marine Chapter, often dating back to the years of the Horus Heresy and so revered as a holy relic and a physical manifestation of the chapter's undying fighting spirit. Terminators are Space Marine or Adeptus Custodes veterans who have earned the right to wear Terminator armor through exemplary service. But of course you came here because of Space Marines in Terminator armour. It's also the name of a franchise that began in 984.M2 based on a type of robot employed by the A.I Skynet for its noble goal of cleaning Earth of human scum (initially humanoid infiltrator type - which a certain race of robots in 40k is based on, but later all Skynet robots came to be called that). Terminator is the border between day and night sides of the planet, also known as a 'twilight zone'. 'If I am to die, I DIE STANDING!' – Dawn of War 2 Terminators, exemplifying the average tenacity of the Chapter's finest.

Sisters of battle terminator