The Leech Hydroe is the main antagonist and final boss of the 2017 3DS videogame Hey! Pikmin, a spinoff of the Pikmin series.
The Leech Hydroe is a green amoeba-like animal that normally feeds on nutrients released from plants by absorbing them. While generally harmless and timid in its natural body, when absorbed to a large amount of Sparklium, its appearance turns bright pink, while its plant host turns into a massive three-headed monster with Venus flytrap-like heads followed down prickly necks onto a grass covered pink body, with appendages made out of roots.
When Captain Olimar flies his spaceship, the S.S. Dolphin II, back towards his home planet of Hocotate, he accidentally warp drives to the wrong coordinate in space, crashing his ship into an asteroid belt orbiting a planet. In the process, his Sparklium Converter unit is detached from the ship and crash lands onto the Leech Hydroe as it slept. The energy released from the Sparklium sent the Leech Hydroe into a frenzy, causing its parasitic urges to grow rapidly out of control.
Although the Leech Hydroe is not fully seen until the end of the game, its presence is sensed throughout Olimar's exploration, as multiple roots similar in color to the Leech Hydroe can be spotted growing across all nine sectors on the planet, possibly indicating that the Leech Hydroe is feeding off the sources of the planet to make itself more powerful.
Upon reaching his 30 thousand Sparklium limit, Olimar reaches the ninth and last sector in the planet, "The Final Stretch", to locate the Sparklium Converter, where he discovers the Leech Hydroe has gone berserk from all of the energy it has consumed and engages it with his Pikmin army to defeat it once and for all. Ultimately, the Leech Hydroe uproots itself and grows wings to gain an advantage, but Olimar and the Pikmin manage to defeat it, seemingly killing it as it turns brown and decomposes.
With its host destroyed, the Leech Hydroe emerges from its remains and attacks Olimar, but trips and falls; in the process the Sparklium Converter pops out of its body, returning it back to its original form. Upon waking up, the Leech Hydroe cowardly runs away, leaving its fate ambiguous.