The Knights of the Underworld (黄泉の騎士団,Yomi no kishi-dan?) are a supernatural species that appear in Sonic and the Black Knight. They are hostile phantoms from the underworld given physical form through armor who work under King Arthur and later Merlina the Wizard. They serve as the enemies fought during the game's various Missions.
The Knights of the Underworld are phantoms of black magic, meaning they have no body to speak of. Instead, they wear pieces of armor to gain shape and physical presence.
The Knights of the Underworld can take a vast array of different forms with their armor. The majority of them resemble humanoid beings while others tends to resemble sea creatures, such as fishes, sea slugs and crabs (one type even takes the shape of treasure chests). However, besides each wearing metallic armor, common features the Knight of the Underworld share are that they each have a single pink with an almost slit-like black pupil glowing medieval symbols on their bodies.
If taking King Arthur into account, it is possible the Knights of the Underworld can appear completely human. However, it is unknown if this occurs naturally or is created artificially through magic, such as when Merlin created Arthur.
Characteristics and Culture
The Knights of the Underworld are seemingly mindless, appearing as non-sentient drones who unquestionably follows the orders of their controller. On their own though, they are quite hostile and aggressive as they usually attack any threats. If including King Arthur as a Knight of the Underworld, it is possible for them to have sentience, though it is not specified if this trait occurs naturally or is created artificially through magic, such as when Merlin created Arthur.
Powers and Abilities
All Knights of the underworld are able to teleport to different locations by emerging from black voids. Humanoid variants tend to be good at using weapons, such as swords, spears, axes and crossbows, though one variant of this type can also possess super strength. The sea creature-like type are capable of shooting energy blasts, the majority of which can create energy attacks with their own effects. Also, the Fish-One variety and a few others are capable of flight thanks to their anatomy.
Whenever a Knight of the Underworld is defeated, it completely dissolves into thin air.
When Sonic the Hedgehog were called into the world of Camelot to stop Arthur by Merlina the Wizard, he faced hordes of the Knights of the Underworld in his quest to get the means to defeat Arthur. After Sonic had finally defeated Arthur, he discovered that Arthur was a form of illusionary Knight of the underworld, created by Merlin. When Merlina then betrayed Sonic, she apparently took control of the Knights of the Underworld and seized them at Sonic and the Knights of the Round Table to keep them from interfering with her plans to make the kingdom eternal, though at an immeasurable cost. Following Merlina's at Sonic's hands, it is unknown what happened to the Knights of the Underworld afterwards.
Unnamed Knights of the Underworld resembling crabs with spider-traits. They are the fastest of the Knights of the Underworld and attack with fast claw swipes. They appear in the Missions after defeating King Arthur and can be defeated with a single attack.
Unnamed Knights of the Underworld resembling Treasure Chests with bat wings. When they appear, they will try to fly away from the player before disappearing. When touched, the grant an amount of Rings.
It should be noted that the Knights of the Underworld appear impervious to the Homing Jump maneuver which can destroy Egg Flappers, indicating that it is the magical power of sacred swords which banishes them, as opposed to mere physical damage. The Knights can also be defeated with strong sunlight reflected off Caliburn's blade, as seen in Crystal Cave.
However, as seen in the opening of Sonic and the Black Knight, Sonic was able to destroy a group of the Knights of the Underworld by blasting through them at high speed, contradicting their invulnerability to physical strikes.
↑"These phantoms from the Underworld have no bodies to speak of–they're given shape by the pieces of armor they wear. When Sonic runs across one of these footsoldiers, he never knows what kind of threat he's facing, as their weapons, tactics, and roles vary" - Description of the Soldier-Ones, Sonic and the Black Knight US website.