Red Chested Squid
A blue squid monster with a red-chest, whom wields a staff in battle. It was shown being fought by Sting. With Dragon Knight's help, the two Riders were able to combine forces and destroy this monster. This monster was seen fighting Wing Knight in a flashback.
"Vent or Be Vented" and "A Rider's Resolve"
A lemur monster armed with a sniper. It tried to abduct a woman only to be caught by Dragon Knight. This three-eyed monster was destroyed by the Rider's Final Vent.
"Thrill of the Hunt"
Wild Psycorogue
A robotic cricket monster that can shoot beams from its eyes. It ambushed Kit and Len at a factory, causing them to transform and fight back. It retreated after taking a hit from Kamen Rider Wing Knight's Sword Vent.
"The Hero of Gramercy Heights"
Fenghuang Monster
A red Fenghuang monster in a phoenix-shaped hemlet. He fought Kamen Rider Dragon Knight and Kamen Rider Sting. He was destroyed by Sting's Final Vent.
"Thrill of the Hunt"
A brown and green Bighorn Sheep monster that attacked Kit and was destroyed by Dragon Knight's Final Vent.
"Semper Fi"
A Water Buffalo-like monster, it appeared when Kamen Rider Spear used his Attack Vent. It was among those who ambushed Sting. It disappeared when Spear command it to.
"Semper Fi"
A Cicada-like monster, seen fighting Kamen Rider Wing Knight in a flashback along with a Red Chested Squid and a blue Longhorn Beetle monster at night.
"A Rider's Resolve"
Sheerghost's evolved form that has blade-like structures on their forearms and are capable of flight. The original Kamen Riders are shown fighting them in a flashback.
"Dark Temptation"
Sheerghost's alternate evolved form with dragonfly-like tails at the back of their heads. The Hydragoons are larger then their previous forms.
"Dark Temptation"
Buzzstinger Hornet
A red-armored hornet monster that wields two needle-blade daggers. He assisted Xaviax's Mirror Monster minions in fighting Kamen Rider Wing Knight and Kamen Rider Siren. He was destroyed by Wing Knight's Final Vent.
"Dark Temptation"
Monsters Episodes 1-10 | 11-24 | 25-40