Discord

Discord was, believe it or not, the original ruler of Equestria after it was founded by the three original tribes. Celestia and Luna saw how miserable for the Unicorn, Pegasi, and Earth Ponies alike. So Celestia thought enough was enough , she and Luna discovered the Elements of Harmony, and imprisoned Discord in stone. After the conflict, the two Alicorn co-ruled the land until the beginning of the legend known as "The Mare in the Moon".