That would be the SS --- a private police force of the Nazi Party, who like many of my most hated groups wore black, but not in field service ( for which they were the inventors of the modern battle smock [ mostly DPM, not black ] ).
Oddly most democratic militarised civil police ( eg: SWAT ) around the world now seem to be fond of intimidating black with full-face helmets. SWAT are what the SS wanted to be when they grew up.