- Main article: Factions (Orsinium)
The Order of Diagna, or sometimes referred to as the Order of the Diagna, is a secular group of knights from Hammerfell known to have been active during the First and Second Eras. Their most notable achievement was leading the thirty-year Siege of Orsinium. The most famous leader of the Order of Diagna was also the founder of the Imperial City's Arena, Gaiden Shinji, who died during the Siege. He was said to have slain hundreds of Orcs by that time, and nonetheless, many fighters of the Order still live by his Credo, "the best techniques are passed on by the survivors..." Any Initiate wishing to join the Order must play the role of the Orsimer in the annual reenactment of the Siege of Orsinium.
- The Elder Scrolls II: Daggerfall (Mentioned only)
- The Elder Scrolls III: Morrowind (Mentioned only)
- The Elder Scrolls IV: Oblivion (Mentioned only)
- The Elder Scrolls V: Skyrim (Mentioned only)
- The Elder Scrolls Online (Mentioned only)