Kelvans are a fictional race featured in the Star Trek multimedia franchise. They appeared in the original NBC television series and were introduced in the 22nd episode of season two, "By Any Other Name". Kelvans hailed from the planet Kelva, located in the Andromeda Galaxy, and were part of the Kelvan Empire. In their natural form, they were described as immense beings with hundreds of tentacles. They were a race of conquerors who preferred to occupy worlds that were already inhabited as part of their personal code of honor.
A Kelvan expedition was left stranded on an M-class planet in 2268. At this point, the Kelvans had transposed their conscious minds into humanoid bodies. They sent out a distress beacon that was intercepted by the USS Enterprise. When the crew of the Enterprise sent a landing party, the Kelvans incapacitated them with a device on their belts which temporarily paralyzed them. They also demonstrated their power by turning two of their crew members into block of chemical compounds. The leader of the expedition, Rojan, told Captain James T. Kirk that they were commandeering their ship and crew for they needed it to travel past the Galactic Barrier back to Kelva.
During the journey towards the Barrier, Captain Kirk came up with a plan to defeat them. The Kelvans were not used to inhabiting human bodies and were now prone to human sensations such as sensory input and emotions. Kirk took advantage of this newfound trait to distract the Kelvans long enough so that he could defeat Rojan. He convinced him to abandon his quest in favor of working with the Federation to find an uninhabited world that they could colonize.