F.A.T.E. (Bionic Fantasy)

The Fatal Age Terminator Engine (F.A.T.E.) is the source of the FATE virus, a major plot device in Prologus: Bionic Fantasy.

Story
When legends arose on Ankoku Nui about the coming of a "Warrior of Time" the Choujintei created a machine he calls the Fatal Age Terminator Engine to cultivate and release a virus which kills people at random when the infected reach 17 years old. Keeping the existence of the machine itself secret, the Choujintei blamed the Shadow Matoran, which he ironically also created, for unleashing the virus and promised immunization to those who joined Dai-SOLDIER and actively helped him exterminate the Matoran remaining on the planet, save for Crono, who was determined to survive at least long enough to expose the truth.

The FATE virus was not contagious, and it only affected humans.

Many years later, the machine was finally discovered by Crono, Gainaz, and Zonan.

Trivia

 * The FATE is a culmination of the concepts behind Sin from Final Fantasy X and the similarly named entity from Chrono Cross, as well as Deus from Xenogears, to a small degree.
 * Before the name of it's source was revealed, the FATE virus was simply called "the virus", and other similar synonyms.
 * Zonan not being affected by the virus even as she reached 17 year old before discovering it was one of the first hints at Zonan being an android.