According to Wikipedia:
Orc (/ɔɹk/) is a word used to refer to various races of tough and warlike humanoid creatures in various fantasy settings, appearing originally in the stories of Middle-earth written by J. R. R. Tolkien and derivative fictions. Orcs are often portrayed as misshapen humanoids with brutal, warmongering, sadistic, yet cowardly tendencies, although some settings and writers describe them as a proud warrior race with a strong sense of honor (for example, the Warcraft series ). They are variously portrayed as physically stronger or weaker than humans, but always high in numbers. They often ride boars, wolves and wargs. In many role-playing and computer games, though not in Tolkien's works, Orcs mainly have green skin (earning the name "Greenskins" in such games as Warhammer Fantasy).