The Nightmare Leeches are minor villains in Digimon Fusion. They are creatures created by NeoMyotismon to drain the energy from his enemies.
Nightmare Leeches are little demon like creatures created by NeoMyotismon. They are shadow-like creature with razor sharp teeth.
Nightmare Leeches were members of the Bagra Army. They were created by one of the Dark Generals; NeoMyotismon. They were used to suck the life energy out of Digimon. After NeoVamdemon was defeated it's likely that the Nightmare Leeches were destroyed as well.