Seahorses are one of nature's Mix-and-Match Critters. Essentially, it is a fish, but with the tail of a monkey, the pouch (in males) of a kangaroo, swiveling eyes like a chameleon, encased in bony armor plating, swimming upright using its dorsal fin, and with a snout more like a snorkel than anything else nature has come up with. These odd features have led it to be associated with Eastern Dragons. According to some legends a seahorse is a baby dragon, and thus seahorses are often tied to dragons. Like Dinosaurs Are Dragons, this is largely an Eastern culture trope: most notably, the Japanese word for seahorse, "tatsu-no-otoshigo", literally means "dragon's bastard child."
- In Fruits Basket Hatori Sohma is one of the Juunishi, specifically the year of the Dragon in the Eastern Zodiac. However, he transforms into a seahorse when embraced, something that is embarrassing and quite dangerous to him if he's not near a body of water. According to Shigure, the fact that he turns into a seahorse instead of a dragon is a sign that the Sohma family curse is weakening.
- Naruto the Movie: Road to Ninja has Seiryu◊, of the Nine Masked Beasts, who is described as seahorse-looking and translates to "Azure Dragon".
- The One Piece character Tatsu is a memory stealing seahorse who dreams of becoming a Sennenryu, a dragon that lives for 1000 years before giving birth and dying.
- In the Yu-Gi-Oh! card game the Kaiser Seahorse can be used as an easier way to summon a Blue Eyes White Dragon in addition to the name "Kaiba" literally meaning "Seahorse" or by extension "Young Dragon".
- There is also a card called Thunder Seahorse which is almost identical to an older card called Thunder Dragon.
- The Horsea line are all classified as "Dragon" Pokemon in the Pokedex, though Horsea and Seadra are not Dragon type Pokemon, but their evolution Kingdra (based on the Weedy Sea Dragon) is.
- Generation 6 has Skrelp, a Poison/Water type Leafy Sea Dragon who evolves into Dragalge, a Poison/Dragon Leafy Sea Dragon.
- In Ōkamiden the new brush gods are the children of the previous brush gods, and the same species the children of Yomigami, the dragon god of rejuvenation are a pair of seahorses.
- In The Legend of Dragoon there's a monster which looks like a winged seahorse with fire on his tail and referred to as "Dragon".
- Metroid had "Dragons" which resemble red seahorses. Dragons are an interesting case because their fire breathing powers are more reminiscent of western dragons, which are unconnected to seahorses.
- The graphics of the dragons from Adventure looks similar to a seahorse.
- The redesign for Manaketes introduced in Fire Emblem Awakening is based on the real-life leafy seadragon mentioned below, invoking this trope.
- Kingdom Hearts has the Tatsu Steed and the Tatsu Blaze, both look like winged seahorses. Additionally, Tatsu is an old Japanese word for dragon.
- Super Mario Land
- Don't underestimate seahorses in Ultima. They might look like they're a normal everyday seahorse, but they're on par with the local sea-serpents. They are not only capable of speech but magic as well, and if provoked they will spit fireballs at you until you flee or are vaporized. You can fight them and even defeat them, but it's honestly not worth it—their HP and strength are ridiculously high, their experience and treasure values stink, and they're natural creatures, meaning that killing them reduces your Compassion and Justice scores. You'd make more profit and be at much less risk of humiliating death just by punching a couple of slimes instead.
Spoony: The instructions book certainly tells you that these sadistic fishfuckers will pump 1.21 gigawatts right up your ass.
- In Virtual Boy Wario Land, Sea Dragon Wario can breathe fire out of his seahorse snout.
- Aquaria plays with this just a bit. Seahorses are friendly, can be ridden around for a speed boost, and whinny when interacted with. Seadragons (see below, under Real Life), on the other hand, are hostile, breathe fire, and roar very loudly when they spot you.
- The Facebook game Dragon City has the Seahorse Dragon, as seen on the page image.
- Weedy seadragons, ruby seadragons and leafy seadragons, aquatic seahorse relatives that have plant-like growths on them for camouflage in their seaweed habitat. While not dragons themselves (obviously), they are named after them and resemble small sea dragons.