The Kelvans were a highly intelligent non-humanoid species, native to the planet Kelva in the Andromeda Galaxy. They ruled the Kelvan Empire with an iron fist. Only a small number are known to have reached the Milky Way Galaxy.
The Kelvans original form compared to humanoids is immense. An adult Kelvan was twice the size of an adult Klingon male. (DS9 episode: "Time's Orphan") The Kelvans also had an incredibly disciplined mind, which allowed them to operate each of their hundred tentacle-like limbs independently, but any Kelvan soldier worth his pay grade would have lost at least ten of them in normal combat. They also had hooked claws on their appendages, a blowhole, and a beak. (TOS episode: "By Any Other Name"; TOS - Strange New Worlds 9 short story: "Gone Native")
The Kelvan society was based in order and discipline. They believed in their innate superiority, and deemed it the fate of lesser species to be conquered and ruled. Ruthless but practical, their goals were expressed in plain, civil terms lacking any indication of blood-thirst. As long as the obedience demanded by the Kelvan Code of Honor was upheld, their conquered subjects were treated with appropriate respect and given some bounded latitude. (TOS episode: "By Any Other Name")
Preemptive strike Edit
Centuries ago, Kelvan scientists discovered that the rising radiation levels in the Andromeda Galaxy would make it uninhabitable by their species within 10,000 years. In response to this threat, the Kelvan Empire sent several multi-generational starships to the nearest galaxies. The explorer crews would spend several generations in their journey, and were ordered to search for new territories and to report on their suitability for conquest and occupation.
One of these Kelvan starships left Andromeda sometime in the 1960s, and reached the Milky Way Galaxy only 300 years later, in 2268. However, the Kelvans were not aware of the galactic barrier surrounding the Milky Way, and their ship was destroyed in the crossing. A small group led by Rojan survived their ship's destruction and were able to reach a Class M planet, where they adopted the humanoid form, believing it would be more suitable regarding the planet conditions.
With a false distress call, Rojan and his team were able to capture the USS Enterprise. Rojan's crew modified the Enterprise with Kelvan technology, permitting the starship to penetrate the galactic barrier, and began the long return voyage to Kelva.
Once the Barrier was successfully breached, Kirk and his senior officers began a systematic subversion of the Kelvan's mission by exploiting their weaknesses: their inexperience with the new sensations offered by their humanoid bodies. Kirk convinced Rojan that his new life as a humanoid could be experienced to the fullest on a world in the Federation, and a robotic envoy to Andromeda could fulfill his mission by delivering a Federation peace proposal to the Kelvan Empire. (TOS episode: "By Any Other Name")
The Kelvans technological knowledge after the launch of their multi-generation starships is unknown, but the technology possessed by Rojan's team when they made contact with the Enterprise was far beyond the Federation's abilities of that period.
Body shells Edit
Kelvans were able to abandon their natural forms in favor of new bodies more appropriate to local environments. This process, which was described by Rojan as "encasing" themselves in "humanoid shells", also had the "collateral effect" of shifting Kelvan personalities toward a humanoid perspective as they experienced life with radically different physical senses. (TOS episode: "By Any Other Name")
Belt device Edit
In their humanoid form, Kelvans carried a device worn on belts around their waist. With a touch, a Kelvan could immobilize multiple targets with a neural field that selectively neutralized nerve impulses to their voluntary muscles or, if necessary, the device cound instantly "distill" a lifeform, suspending animation and encoding the target's physical form and personality into a compact dehydrated porous cuboctahedron solid, composed of the target's base minerals. The person could be reconstituted from their solid state at any time, but if the solid was damaged, the process cound not be reversed. These belt devices had a central projector radiating from the planet surface. The projector was shielded by a metallic substance, similar to diburnium, but considerably more dense and impervious to phaser fire. (TOS episode: "By Any Other Name")
Multi-generational starships Edit
Kelvan multi-generational starships were capable of sustained life through the voids between galaxies, wich offered no way to replenish their supplies. Their propulsion systems allowed them to cross these distances in a very small period of time, considering that a Constitution-class starship running at maximum warp would take thousands of years to complete the journey. They were also capable of trespassing the great barrier, although they've lost their ship due to the fact that they didn't know about its existence when they crossed it in the first place. (TOS episode: "By Any Other Name")