The Kobali were a humanoid Delta Quadrant species. Their method of reproduction was unique and their most distinguishing characteristic: they added to their population by reanimating the deceased corpses of other species, altering their DNA to transform them into fellow Kobali.
They were warp-capable, appearing to have a technology level likely not dissimilar to that of Starfleet. While not generally a hostile species, they were highly protective of their own and would go to great lengths to find and return any member of their society who attempted to flee. (VOY: "Ashes to Ashes")
Method of reproduction
Their most distinctive characteristic, and perhaps a unique quality to their species, was their method of "reproduction". Rather than sexual reproduction or other familiar techniques (such as asexual reproduction), the Kobali added to their population by obtaining the corpses of deceased humanoids, reanimating them and heavily altering their DNA to match that of their fellow Kobali. This ability seemed to indicate they possessed a form of medical technology highly different from and, by virtue of this ability, more advanced than, Starfleet's or most other humanoid species.
The reanimation process
Over a period of several months, the DNA of the reanimated lifeform was altered by means of a genetic pathogen that converted most of the alien's DNA into a Kobali protein structure. These biochemical changes affected every part of the body, leaving only trace amounts of the original being's DNA.
The reanimating process involved more than merely "resurrecting" corpses and altering the DNA and physiology of the (formerly) deceased. They also trained the newly-reanimated to adapt to their culture and language. This was necessary to help acclimate the new Kobali as he or she adjusted to becoming a member of a new race. It also helped ease the shock of new Kobali finding themselves alive again, albeit in a completely different physiology and culture.
The Kobali were humanoids with grayish skin and hairless heads. Their internal physiology was quite different from that of Humans, as The Doctor discovered. They also possessed unusual tastes in food: for example, meals normally considered delectable by Humans and many humanoids were strongly disliked by Kobali.
More specifically, Kobali physiology differed markedly from that of Humans. They had a six-lobed brain and a binary cardiovascular system. The effect of the genetic pathogen could not be reversed by Starfleet medical technology because there was not enough original DNA present after the alteration to do so. It was, however, possible to change a person's appearance by inaprovaline injections, which needed to be repeated to maintain the lifeform's previous appearance. This only helped for a short time because the Kobali genetic pathogen counteracted the changes.
There was little variety in the Kobali diet; their main food looked like gray paste. When they tasted other foods such as a Jiballian berry salad, it had a metallic flavor to them.
Kobali had a talent for sensing and manipulating wave phenomena. Vyk'tiote, translated roughly as "crumpled dance," seemed to be their specialty.
Society and culture
Once a new Kobali was revived from a corpse, he or she would be placed within an adoptive family. Because this was their method of reproduction, the adoptive parents treated their new "child" with as much love and compassion that often accompanied sexually-produced offspring or traditionally adopted children. Still, it could take quite some time for a new Kobali to adjust to the shock of being revived, transformed, and placed in a new family.
Reanimating was a most important part of Kobali culture, which could sometimes lead to conflict with other species' burial customs. Reanimation caused extensive memory loss, usually rendering the formerly deceased entirely new beings, with a new and distinct Kobali personality. Some new Kobali, however, remembered parts of their former life, known to the Kobali as kyn'steya. There were also some who remembered so much of their previous lives that it caused them to escape the Kobali in search of their former lives. Those that did were searched for extensively by other Kobali to return them.
Their medical capabilities were unique and relatively advanced, for they could reanimate those who had been dead for more than two weeks. The Kobali also had a high regard for every life they reanimated and assimilated, which was illustrated in their adage, "Never harbor anger towards those who have brought you death, for they gave you the chance to live again."
They are quite stubborn. Even if those who retain their memories wish to leave for their old lives, Kobali refuse the request and even hunt them down and hound them relentlessly to wear down their willpower to make them willing to give up.
Encounters with Voyager
The Kobali made first contact with Starfleet in 2376 via the starship USS Voyager when they were searching for Jhet'leya, a Kobali kyn'steya who escaped her family in search of her former life as Ensign Lyndsay Ballard, who had served aboard Voyager. The Kobali attempted to track down Voyager immediately after she fled from them. This contact did not proceed smoothly, for initially she did not wish to return. Tensions escalated to the point of the Kobali ship opening fire when demanding her return, which Captain Janeway insisted be left up to "Ballard". Eventually, however, she rejoined her Kobali family voluntarily, removing the previously touchy relations between Voyager and the Kobali ship and forging a better friendship and understanding between the two cultures.
The Kobali had been part of Bryan Fuller's original pitch for "Workforce", in that the crew (except an away team made up of Chakotay, Tom Paris, and Neelix,) would have originally died in a Titanic-like disaster, only to be revived without their memories, and discovered making a life in Kobali society. (Star Trek: The Magazine Volume 2, Issue 2, p. 84)
The Kobali appear in Delta Rising, the second expansion to Star Trek Online, set in the year 2410; their adopted homeworld of Kobali Prime, a moon orbiting a gas giant, is a major "adventure zone" with a variety of missions, much like the Dyson sphere added in Season 8. The Delta Alliance, a coalition formed by the Federation, the Klingon Empire, and the Romulan Republic, arrive on Kobali Prime to find it under siege by a resurgent Vaadwaur Supremacy.
Captain Harry Kim, assigned as Starfleet's liaison to the Kobali, suspects that the Vaadwaur have something other than conquest in mind, and (with the aid of the player) discovers that Kobali Prime was once a Vaadwaur colony world, and that stasis pods containing Vaadwaur soldiers are buried underneath the surface. The Kobali had taken possession of the pods and were using Vaadwaur bodies recovered from the failed pods for their reproductive cycle. The Vaadwaur in turn were attempting to reconquer the planet in order to recover the soldiers and add them to their forces.
During his time with the Kobali, Harry is reunited with Jhet'leya, who has recovered and reanimated the body of the 'original' Harry Kim (blown out into space during a hull breach in "Deadlock"). Much as Jhet'leya did, the other Harry eventually comes to terms with his new existence as "Keten".
The storyline also establishes that the Kobali's bizarre reproductive method was developed after genetic engineering experiments accidentally rendered the entire species sterile.