The Knights of Order are a type of Daedra who serve Jyggalag, the Daedric prince of order. They are found in the Shivering Isles only during the Greymarch. They wear a crystalline armour, similar to the obelisks that are found throughout the Shivering Isles, and are summoned by the Priests of Order at said obelisks.
Knights of Order are a humanoid daedra, taller than most humanoids in the series. They wear crystal armour and wield crystal swords. According to Sheogorath and his chamberlain, Haskill, they don't have a single original thought in their heads.