Imperial Elite Guard

The Imperial Elite Guard is a special military unit composed of highly-trained Shock Troopers. In addition to the defense of important Imperial worlds such as Coruscant and Bastion, the Guard is tasked with protecting the government's most important officials, such as the Imperial Head of State and the Council of Moffs. Due to their unique status within the Stormtrooper Corps, the soldiers of the Guard are distinguished from the rest of their fellow Shock Troopers by black armor. =Sources=
 * Wookieepedia