Hond

The Hond were "the primordial ooze" given sentience as an embodiment of the concept of pain. Hailing from the Dark Times, they were hypothesised by the Tenth Doctor to have been the result of "the Universe not quite knowing what life was like yet" when it created them. Thanks to a time paradox, the Hond eventually emerged into a later era of the universe and threatened the Dalek Empire, forcing the Dalek Prime Strategist to seek out the Doctor for help.

Biology
The Hond, as the sentient embodiment of a concept, could only be destroyed if freed of the pain that formed the core of their being. Individual Hond, being less full of suffering, were capable of some amount of reason, but proximity to the rest of the horde would make them go more and more incoherent. The horde was capable of travelling through space in the loose form of a sphere. (COMIC: Defender of the Daleks)

Like most lifeforms from the Dark Times, (PROSE: The Knight, The Fool and The Dead) they were immune to death and, indeed, capable of a form of regeneration. When blasted by a Dalek gunstick-fire, a Hond would collapse into ooze for a few moments, but actually feed on the suffering the blast had caused it and reform stronger than before. (COMIC: Defender of the Daleks)

History
During the Dark Times, the Hond remained "in the shadows", with a Data Worm that raided the Archive of Islos long after that era describing them as a "Forbidden Race" and a "terrible miscreation". Being that the Hond could only experience life via pain, the only time the judgement of the Kotturuh was considered mercy was when they judged the Hond. (PROSE: Secrets of Time Lord Victorious) They were therefore known to have died out, (PROSE: The Restoration Empire) but the Tenth Doctor's actions in the Dark Times (PROSE: The Knight, The Fool and The Dead) caused changes to time, allowing for the return of the Hond. (COMIC: Defender of the Daleks)

The Hond were unleashed by the Dalek invasion of the Archive of Islos, (PROSE: The Restoration Empire) and immediately made plans to dominate N-Space. They released their slave to destroy the Daleks, (WC: The Sentinel of the Fifth Galaxy) due to a deal they had made with the Chief Archivian. (WC: The Archive of Islos)

After the Daleks defeated the Slave of the Hond, (WC: Day of Reckoning) the Honds themselves attacked, despite the Daleks' attempt to create an alliance with them. Unable to defeat the Hond by conventional means, the Emperor of the Restoration recruited the Tenth Doctor to defend Skaro, telling him the Hond were seeking to destroy the Daleks, before, according to the Emperor, destroying the rest of the universe and then themselves.

On Skaro, the Doctor and the Dalek Prime Strategist entered the Vault of Obscenities, where they confronted their first Hond, who declared that they would "kill all." After dispatching him by trapping him in a crystal cage, the Doctor got to work on the matter of defeating all the Hond. Eventually figuring out their true nature as creatures of suffering, the Doctor managed to rewire all the weapons in the Vault into a huge psychic transmitter, hitting the Hond horde with a ray of magnified relief. As they began to evaporate due to the hurt being gone, one Hond thanked the Doctor for his act of kindness. (COMIC: Defender of the Daleks)

Behind the scenes

 * As "the primordial ooze given sentience" and becoming a time-travelling enemy, the Hond are reminiscent of the ancestor cells from the BBC Eighth Doctor Adventures, a potential identity of the Enemy in the War in Heaven, although a formal link between the two is not drawn in COMIC: Defender of the Daleks. Later, in Exit Strategy, the Dalek Prime Strategist recalled the Hond as an "impossible enemy".