In the Guyver manga, the Libertus are an advanced series of Zoanoids employed by Zeus' Thunderbolt. They were developed by Dr. Alfredo Hekkaring, a Cronos scientist abducted by Agito Makishima. The doctor had a personal stake in their creation, since he hates Hamilcar Barcas and wants to beat him at his own game. He succeeded in creating a form of Zoanoid that has consistently proven to be superior to their Cronos counterparts. These Super-Zoanoids are drawn from the ranks of Zeus' Thunderbolt; they are volunteers, although they have not been told the entire truth about their condition.
Libertus are substantially stronger than Hyper-Zoanoids, displaying enormous strength even in human form. On the battlefield, they are constantly accompanied by their commander, the female proto-Zoalord Griselda. She coordinates their actions, protects them from Zoalord control interference and has the ability to heal their injuries through touch. At one battle, Griselda and four Libertus were able to defeat over 400 Zoanoids and Hyper-Zoanoids.
They have the ability to change their form, adapting to a secondary mode equipped with powerful bio-blasters on their shoulders; they can change back to combat mode at will. They can also transform into a tertiary kamikaze mode; this change is irreversible, since it changes most of the body to an organic explosive, which then explodes.
The Libertus pay a high price for their abilities: they have to spend their time off the battlefield in regeneration tanks to maintain their energy levels, and even so their life span is shortened to about two years.