The G-Virus is featured throughout the Resident Evil franchise.
A mutagenic pathogen which causes the host to become a big, constantly evolving, practically unstoppable killing machine, with exceedingly high attack power and immense vitality, in addition to the ability to regenerate and mutate so quickly the carrier virtually loses its mortality.
The purified virus can be injected directly into the host, or a mutated host can implant a small larvae, called a G-embryo into another host. The latter mode of transmission is most successful when the host and the new victim are genetically similar. The virus would later be merged with the T-virus by Umbrella scientists in an attempt to balance the G-virus' rapid evolution with the T-virus' stability, creating an extremely dangerous, electromagnetic-capable variant called the T+G virus.