The Heylin Knights were powerful Weapons of War shaped like Giant Armours in Xiaolin Showdown – Return of the Heylin Empire, at their smallest they stood at Seven Meters Tall and at their Highest they stood at Fourteen Meters, they were the Super Weapons of the Heylin Empire during the Lost Age that almost brought their Xiaolin-aligned enemies to their knees.
- Xaphian the Demon Knight - Pactmaker: Maverick Daimos. Element: Darkness. -
- Adolmaea the Sun King - Pactmaker: Maverick's Best Friend and General (deceased); Mason Daimos (currently). Element: Fire and Energy. - The Sun King can be thought of as the Leader of the Knights, thus making him presumably the most powerful of their rank, it wields a Double-sword as a weapon and it can also make a yellow energy shield as well as float. This Knight stands at 14 meters tall.
- Luthia the Moon Maiden - Pactmaker: Heylin Empress (deceased - childbirth sixteen years prior); Rebekah Daimos (currently). Element: Water and Healing. - The Moon Maiden and it is the only female amongst the Knights it also possess elemental and healing powers that the other Knights do not possess, it is the only long-range Knight that can fly and utilizes a powerful bow and arrow which it uses for long range attacks. This Knight stands just over 7 meters tall.
- Wizel the White Knight - Pactmaker: Unnamed General (deceased); Seth Raiden (currently). Element: Neutral/Energy. - The White Knight is the most basic of the Knights and can float, it wields a Sword and a Shield, it eventually comes to wield the Holy Sword which is the only weapon capable of damaging the Sun King and can only be wielded by the White Knight. It stands about 8 meters tall.
- Larvayne the Dragon Knight - Pactmaker: Unnamed General (deceased); Chase Young (currently). Element: Earth/Aerial Combat. - The Dragon Knight is a winged member of the Knights that wields a Trident-Lance, it is believed that it can fly and it can easily match itself against the most powerful of Supernatural Creatures, with the Divine Lance it can damage all of the other Knights except the Sun King and the Devil Knight. It stands about 9-10 meters tall.
- Dinivas the Black Knight - Pactmaker: Unnamed General (deceased); Raimundo Pedrosa Daimos (currently). Element: Wind/Agile Combat. - The Black Knight is the fastest of the Knights and is able to grow two Black Wings which gained it its nickname: Ebonwings, Dinivas has similar fighting capabilities to the White Knight and can simulate poison on its blade that can he dangerous if stabbed in a vital place of the Knights, even without its wings it is the most agile of Knights. It stands exactly 7 Meters tall.