The Hunger

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

Biology
The Hunger was artificially created in a lab, 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 was 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. (K9TV: Black Hunger)