|This article is about a/an Mirror Monster in Kamen Rider Ryuki.|
Hydragoons (ハイドラグーン Haidoragūn, Episode Final): Blue dragonfly monsters that are the evolved forms of Raydragoons, and thus the final form of the Sheerghosts. Hydragoons are more dragonfly-like than the other forms and are much larger, with their body and tail being at least 10 feet long. They are able to fly up to 900 kilometers per hour, can launch harpoon-like claws that can retract with whatever they grab, and have fangs that can rip through steel.
Kamen Rider Ryuki: Episode Final
One bursts out of a Raydragoon that Knight was fighting, chasing him into the sky and snagging him with a harpoon claw, dragging him back to it. Darkwing knocks Knight free, and he defeats the Hydragoon with his Final Vent.
Many more emerge from building windows into the real world in a massive swarm of Raydragoons and Hydragoons, attacking a crowd of civilians before Ryuki Survive and Knight Survive fly into the swarm on Dragranzer and Darkraider, easily taking out individual monsters but being severely outnumbered.
Kamen Rider Decade
Kamen Rider Wizard
Another massive swarm of Hydragoons joins Amadum's army of his strongest monsters to fight the Heisei Riders, most Riders taking out at least several in one way or another.
Kamen Rider Zi-O
A massive swarm of Hydragoons were one of the various monster groups that were summoned in the World of Zi-O due to Swartz merging all of the worlds of the Kamen Riders together.
- The first Hydragoon's "eruption" from the Raydragoon is similar to the emerging method of Chestbursters from the Alien franchise.
- Kamen Rider Ryuki: Episode Final
- Kamen Rider Decade
- Episode 1: Rider War
- Kamen Rider Wizard
- Episode 53: Neverending Story
- Kamen Rider Zi-O