The "Angels of Death." Genetically enhanced warriors organized into Chapters like the Ultramarines and Blood Angels.
The Emperor's personal bodyguards. They are elite, gold-armored superhumans who are even more powerful than Space Marines. Warhammer 40k - Warriors of the God Emperor
If you are looking to build an army or learn the lore, these are the primary "Warriors" that defend Holy Terra: The "Angels of Death