A virus is a microscopic particle that can infect a host cell. Viruses are incapable of replicating without infecting a cell. At their most basic, they are genetic material contained within a protective protein.
- "The Abyss" - A virus found deep underwater that allowed for deep sea animals to adapt and survive.
- "Ancient virus" - A virus long since fused with queen ants. All queens that descend from an infected queen share her traits.
- Progenitor - A virus existing naturally within the "Stairway of the Sun" flowers in west Africa. Those who are not killed from the infection become incredibly strong.
- "t" - A merger of the Progenitor virus with leech deoxyribonucleic acid.
- Neo-t - A virus developed by Mylene Beardsley before the development of the G-virus
- t-Veronica - A merger between the ancient virus and Progenitor.
- "G" - A mutation of the Type-B Progenitor variant that increases cellular reproduction - making the infected essentially immortal.
- "t+G" - A merger of the G-virus with t-antibodies. Those infected have the ability to conduct a bio-electrical field.
- t-Abyss - A t-Virus variant created by TRICELL alongside the FBC, combining "The Abyss" virus and the t-Virus.
- Uroboros - Another man-made variant of Progenitor, developed in conjunction by Albert Wesker and TRICELL.
- t-Phobos - A virus developed by Alex Wesker that triggered mutation when the subject experienced fear, unless they were able to overcome it, adapting them to the virus.
- "C" - An infectious agent, developed by The Family and Carla Radames, that is a cross between an advanced strain of the t-Veronica virus and G-Virus.
- Cameron Virus - An unidentified virus created by Dr. Cameron as she treated herself for infection. Those infected can move their consciousness into other organisms, allowing them to escape undetected.
- X-virus - A virus only present in DC-canon.