The Hunger

''' The Hunger was a genetically engineered swarm of bacteria and archaea who had been tweaked to perfection as relentless killing machines, devouring anything in their path.

Biology
The Hunger were artificially created in a lab, Drake mixing together Earth's most ravenous microbes with those from other planets such as Pluto. In fact, Plutonian bacteria were the deadliest in all the cosmos. Their hibernation mechanism was removed purging them of rest and leaving them as nothing more than monsters with an insatiable appetite for destruction and carnage. They appeared as a giant cloud of fuzzy black pixels. They were contained within a nanotechnological device. (K9TV: Black Hunger)

History
The Hunger were created by Inspector Drake to resolve London's litter crisis but they got out of hand when Darius interfered, using them to clean up the mansion. His attempts to return them resulted in disaster as they broke loose and headed for the open where if left to their own devices they would consume the entire globe. K-9 managed to defeat them by imprisoning them within his own body. When he was revived by his regeneration unit, the bacteria would most likely have been destroyed as the device repaired any damage he had sustained in the past including the loss of his collar (K9: The Eclipse of the Korven)