3. T-Virus – Resident Evil
One of the most well known and popular examples of a fictional disease is the "t-virus" from the classic survival horror game Resident Evil, known simply as Biohazard in Japan. The t-virus serves as the catalyst for the numerous zombie outbreaks that place in the series, possessing mutagenic properties that enable it to rapidly transform organisms.
The origins for the t-virus date back to 1966, when an expeditionary team led by Oswell E. Spencer, Edward Ashford and James Marcus discovered an ancient retrovirus embedded within a rare species of flower. Upon further research, this retrovirus was reverse engineered to form the basis for what would become the t-virus.
Throughout the 1960s, Oswell Spencer conducted a number of ruthless experiments on human test subjects with the virus, with the grandiose vision of using its potential to create a race of superior human beings, which he himself would rule over as its leader. However, the strain would prove to be incredibly virulent, resulting in high mortality rates and in most cases leading to a state of living undeath in its victims.