Shin Teikoku Gear (The New Empire Gear)
A mechanical empire based at the Neograd fortress at the South Pole (cf. Black Magma) which plots world conquest. Gear is an empire founded by Doctorman, a scientist turned cyborg. He is flanked by his lieutenants, the Big Three. Gear has five specialized monsters who come back episode after episode - a radical departure from having a new monster every week. From their South Pole base Neograd, Gear launches their Mecha Gigans, weekly fodder for the Bio Robot.

Doctor Man
Civilian Identity : Dr. Hideo Kageyama
Having enhanced his intellect and body with cyborg implants, Dr. Kageyama plans to conquer the world with his army of mecha humans.
Has a son, Junichi.

Allegedly the son of Doctorman. Later exposed to be a mere mechaclone (android) modelled after Shuuichi, Dr. Man's son. Junichi (the real son) and Silver, disguise themselves as the Black Prince to infiltrate Neograd.

The Big Three:

Meison (Mason)
The leader who once plotted against Doctorman himself. Armed with a staff which fires bolts. Later rebuilt and armed with Meison Rockets and Meison Machinegun.

The female member of the Big Three. Uses beam weapons and leaves the dirty fighting to Faracat. Often disguises herself as human in her schemes. Later rebuilt and armed with Fara Fire Storm and Fara Kiss (blows an explosive flying kiss).

As strong as a whale and less than half as smart. Likes to work with the monster Ju-Oh a lot. Initially armed with a huge axe, later upgraded and armed with Black Mace, Iron Paw.

Farrah's bodyguard who did the dirty work (i.e. beat up Biomen). Faracat is quick, agile and acrobatic. She has claws for weapons and uses twin nunchukus as well.

Footsoldiers in black with silver heads and red eyes.

Silva Hakaider (Bio Hunter Silver)
Dark Knight-like Biohunter, a robot from Bio Star programmed to kill anything with Bioparticles. Given half of the Bio Particles, became maniacal and with his robot, Balzion, helped destroy Bio Star. Now armed with Nega Bio Energy similar to that which killed Yellow Four, arrived on earth to locate and destroy the other group with Bio Particles - Bioman. He was not a member of Gear and they fight each other as well.

Silva's giant robot