The Blisk are a bunch of freaks who attacked Earth around the same time as Cryptosporidium and Pox did. However, they preferred the method of invasion that involved converting Humanity into Blisk Mutants, which rendered them useless to the Furons as their DNA was corrupted. Despite being wiped out in the Furon-Blisk War, the Blisk were somehow able to dispatch one ship to Earth before their fleet was totally destroyed, and thus the race survived.
After crashing in Russia they set up an alliance with the USSR and the KGB and went about trying to take over the world. Luckily (sort of) for Humanity, Cryptosporidium was there to stop them and after several engagements the Blisk were utterly destroyed.