- Gender: Male
- Age: Unknown
- Hair: None
- Eyes: Blue
- Nationality: Unknown
- From the manga Biobooster Armor Guyver, by Yoshiki Takaya
- First Appearance: Chapter 12
Another member of the Hyper Zoanoid Team 5, Gaster is a high-mobility artillery support zoanoid. The huge growths upon his shoulders house explosive chemicals, which he can project with the bioorganic missiles implanted there, or spray from the nozzles upon his wrists. Though not incompetent in close combat, it is not his forte.
For some reason, his human form looks slightly inhuman, with pointed ears. Whether this is a natural mutation, or some result of his zoanoid processing, is unknown.