Those of the Orcs that were in the direct service of Sauron and his Dark Tower of Barad-dûr (which in the Orcs' own tongue was known as Lugbúrz). These Orcs carried the emblem of the Red Eye (and indeed were also known as the 'Orcs of the Red Eye'), and had a fearsome reputation as warriors. Many of them were large fighting Orcs of the kind known as Uruk-hai, but we know that other lesser members of Orc-kind could also be found within Mordor.