Bio-Vipers are Cobra's genetically engineered foot soldiers created by Dr. Mindbender. A Bio-Viper typically appears as living goo that takes a roughly humanoid shape, but there have been several variants:
- The prototype version, which was shorter and a bit more monstrous.
- Mecha-Vipers, which are normal Bio-Vipers fused with Destro's Exo-Armors.
- The Techno-Viper, a large, four-legged creature with tentacles that could absorb energy and control machinery.
- Shadow-Vipers, ninjalike troops under the command of Storm-Shadow.
- "Patient X"
- The "Sewer Monster", which was accidentally created by Mindbender when trying to duplicate Patient X's abilities.