Discord is an ancient spirit of chaos and disharmony with the ability to effectively alter reality. He is stated to be a draconequus, a chimeral creature. Initially, he was prone to overconfidence and arrogance, while being a manipulative and mischievous trickster. He ruled Equestria approximately 1000 years before the show's setting, but was overthrown by Princess Celestia and Princess Luna, via the Elements of Harmony, which turned him to stone.
The episodes The Return of Harmony: Part 1 and Part 2 serve as his debut, where he is accidentally freed by the Cutie Mark Crusaders. Though he manages to temporarily corrupt Twilight Sparkle and her friends, they are able to overcome his manipulation and reimprison him. He reappears in Keep Calm and Flutter On, where the Mane Six are tasked with reforming him. While Discord attempts to ensure that he is never reimprisoned, he eventually turns to the side of good due to Fluttershy's genuine offers of friendship.
Discord's latter appearances show him as being good, though he retains his trickster ways. In Princess Twilight Sparkle: Part 1 and Princess Twilight Sparkle: Part 2, it is revealed that his Plunder Seeds had corrupted the Everfree Forest. However, the seeds had been planted before his reformation, and had taken much longer to grow that he anticipated. Discord would later claim that he neglected to mention this to allow Twilight to learn a lesson about being a princess. In Three's a Crowd, he pretends to be sick to get Twilight and Princess Cadance to care for him, only to truly become sick at the end of the episode.
In the Season 4 finale, Twilight's Kingdom, Discord is tempted back to evil by Lord Tirek, and helps to steal the magic of ponies, but ends up betrayed himself. Discord realizes this and truly reforms, which eventually leads to Tirek's defeat by the Mane Six.
Discord is voiced by John De Lancie.
Discord was released as both a Funko Figurine and a Mystery Mini. 1 out of every 24 of the larger figurines was an exclusive chase figurine.