Fear (virus)

The Fear virus was one of a pair of biological weapons created thousands of years before the 22nd century. The other was named Loathing by the Eighth Doctor.

The testing ground for Fear and Loathing was the atmosphere of Jupiter. The makers apparently abandoned their project, leaving the two weapons in a stalemate as they fought each other for millennia. The balance was upset by Farside Station, where an artificial version of Fear was created and took over the station so it could finally destroy Loathing. The Eighth Doctor was able to neutralize both. (PROSE: Fear Itself)