According to the Silmarillion, orcs are a corrupted race of elves, either bred that way by Morgoth, or turned savage in that manner. The Dark Powers tortured, corrupted and bred the captive Elves until they became the vile Orcs.

Elder Scrolls orcs are very close to this version. They were changed when their god Trinimac was eaten by Boethiah, turning him in to Malacath and all of Trinimac’s elven followers in to orcs. Except in this case they’re still just regular people who have some large-scale bad luck and have often been discriminated against, there’s not anything evil or corrupted about them