6.) T-Virus
Featured in: Resident Evil 1-3
Source: Evil Bioengineering Pharmaceutical Company
Effects: Dry skin, confusion, zombie apocalypse

Whether in a film or video game, the Resident Evil series has never been known for its sophisticated story telling. What the series lacks in coherent plot, it makes up for in nasty bio-engineered super plagues released upon innocent populations. The most famous of these plagues (and the one featured in the film trilogy) is Umbrella Corp,'s first, the zombie-making T-Virus. Originally designed to create the perfect bio-weapon, the T-Virus mainly caused inhabitants of a small mountain city to eat each other.

Worse than Pig Flu?: The T-Virus became uncontainable to a level that forced US Government to dramatically blow Raccoon City off the map. Too bad that did nothing to contain Umbrella's other viruses: the Progenitor virus, the T-Veronica virus, the G-virus, Las Plagas, Uroboros virus, and a dozen or so other variants.