Gou Shiro/Red One
- Ace Pilot
- Friend to All Living Things
- Law of Chromatic Superiority: Shirou can understand animals, but nobody else is shown to have unmorphed powers. He's also the only one to be linked to the Dr. Man part of the plot through his father.
- The Leader
- Playing with Fire: Fire Sword
Takasugi Shingo/Green Two
- The Lancer: He is the Number Two after all, but he really cements himself in this position once Mika bites it.
Nanbara Ryuuta/Blue Three
- Punny Name: His Bioman codename is a pun on how the Japanese pronounce "Bruce Lee".
Koizumi Mika/Yellow Four I
- Four Is Death: Played quite straight.
- Hot Scoop
- Killed Off for Real
- The Lancer: She was the most hesitant to be part of the Bio Team.
- Little Dead Riding Hood: Subverted that she died as Yellow Four, but she wears red as casual clothes so...
- Real Life Writes the Plot: The main writer had plans for Mika that ultimately went unrealized after the actress left the series so early.
- Shock and Awe: Thunder Sword
- Taking the Bullet
- Tomboy and Girly Girl: Tomboy to Hikaru's Girly Girl. (Originally)
Yabuki Jun/Yellow Four II
- Action Girl: Very much so, especially since her actress did her own stunts.
- The Big Guy: By virtue of being the Action Girl.
- Legacy Character
- Martial Arts Headband: You don't ever see Jun without wearing one (and it fits her role too). Even one episode had this weaponized by the villains by replacing it with a time bomb!
- Shock and Awe: Thunder Sword
- Tomboy and Girly Girl: Tomboy to Hikaru's Girly Girl. (Replacement)
- Why Did It Have to Be Spiders?
Katsuragi Hikaru/Pink Five
- Barrier Warrior: Pink Barrier
- The Chick
- Holy Hand Grenade: Laser Sword
- Tender Tears: She's the most emotional of the Biomen and tends to cry easily.
- Tomboy and Girly Girl: Girly Girl to both Yellow Four's Tomboy.
- Gender Flip: Even though he's technically a sexless automaton, he addresses himself as a male in the Japanese original. In the English dub however, he was made female.
- Robot Buddy
- Combining Mecha: Composed of two jets (Bio Jet 1 and Bio Jet 2).
- Humongous Mecha
- Mechanical Lifeform: It is shown that Bio Robo has a will of its own when it runs away during Silva's first appearance.
- Big Bad
- Morally Ambiguous Doctorate: That 'Doctor' title certainly doesn't come from medical expertise.
- Was Once a Man
- The Dragon
- The Starscream: This is implied to have been the case in the series' past; though never implemented on-screen.
Bio Hunter Silva
- Big Bad: He reappears as one of the main antagonists of Kamen Rider × Super Sentai: Super Hero Taisen.
- Blade Below the Shoulder: Both which can be fired like arrows.
- Catch-Phrase: Hakai! Hakai! Hakai! (Destroy! Destroy! Destroy!)
- The Dreaded: He possesses Anti-Bio Particles that are more powerful than those used to kill the first Yellow Four (Even though he doesn't manage to kill any Biomen with them). Peebo had a very good reason to fear him.
- Evil Laugh
- Expy: Based on Kikaider's nemesis Hakaider.
- Hero Killer: Less on the Killer part, but he does put up one hell of a fight.
- Humongous Mecha: Pilots one.
- Wild Card