[Name] The Plague of Undeath [Source] Warcraft III [Symptoms] 
The Plague is responsible for the entire Undead race. It can re-animate dead creatures with a reasonable degree of sentience. However, the creature is usually dominated by the undead command structure, but they can escape from the tyranny of undeath. It also causes the soil beneath and around Undead structures to change into a substance known as Blight, which is poisonus to most plants.