Royal Guards were the main security force used to protect the ruler of the Galactic Empire, Emperor Palpatine.
They were some of the most battle-hardened soldiers in the Imperial Army, being trained in various fighting styles, from hand-to-hand combat to be incredibly accurate with a blaster. Many Royal Guards were originally members of the Galactic Republic's Blue Guard, and some were even former members of the Imperial Stormtrooper Corps. After Palpatine's death at the hands of Darth Vader, many Royal Guards either went into exile, in order to hide from the New Republic, while most Royal Guards committed suicide, punishing themselves for not protecting Palpatine. Some members of the Royal Guard wore red stormtrooper armor, similar to the Crimson Stormtrooper.