"What?! Bring them back?!" Discord laughed even more. "My little fruit fart, I can't rightly bring back what I didn't destroy! It's your benevolent horse queen's friendship laser that did the unthinkable!"
- Eljunbyro, "My Harmony"

Discord is a spirit of chaos and disharmony who manifests himself as a Draconequus, and who attacked Ponyville sometime before the beginning of the Austraeoh series. After the Elements of Harmony backfired and killed their bearers, Discord was turned back to stone singlehandedly by an enraged Rainbow Dash, who then stomped his statue to pieces. However, even after his bodily form was destroyed, his chaotic essence infused itself into Rainbow's body instead, and is now slowly killing her. Whenever Rainbow Dash is separated from the Element of Harmony for an extended period, she morphs into a form of him; unintelligent and brutal, but sharing many of his other features.

Princess Celestia states that Discord is one the chief among the "chaos lords" that dwell primarily on the dark side of the plane.

Starting in Ofolrodi, Discord manifested himself as one of the ghosts attached to Rainbow Dash. He appears to be able to "trap" the other girls inside the Element for a time. He appears primarily through whatever reflective surfaces happen to be nearby.