Oprichnik (опричникъ) was a member of a private army (Oprichniks) devoted to the service of tsar Ivan the Terrible during the oprichina times (1565-1573).
The Oprichniks were responsible for the torture and murder of many innocent people in Russia. It is said that they dressed all in black and bore the insignia of a dog's head and a broom. Also, they used to ride black horses in order to ispire terror.The dog symbolized that they would chase the tsar's enemies, the broom meant that these enemies would be swept away.