- "You fight for control of nations...we dominate entire worlds. We extend our will across time. If your race were to endure for a million years, you couldn't begin to approach what we've accomplished."
- —Vosk, 1944[src]
The Na'kuhl were a sapient, humanoid species native to the class M planet Na'kuhl Prime in the galaxy's Alpha Quadrant. They were grey-skinned and yellow-blooded, and notable for their isolationist culture. In the 29th century, a faction led by General Vosk was a major player in the Temporal Cold War. By the 31st century, they were Federation members and represented in Starfleet. (ENT episode: "Storm Front", STO - Future Proof mission: "Stormbound", STO short story: "No Profit But The Name")
The Na'kuhl were humanoids with bat-like features and parchment-yellow skin, bony-looking faces with bright red eyes and bald heads with many visible veins. They are also notable for being one of a handful of species with iridium-based blood. Because of that, they are extremely light sensitive. (ENT episode: "Storm Front")
The Na'kuhl people were extremely isolationist, and had rejected almost all diplomatic contacts throughout their history, although they were rumored to have trade agreements with the Breen Confederacy by the 25th century.
In 2410, a Tholian fleet which had stolen the Tox Uthat from a time traveling Kal Dano headed for the Na'kuhl system in order to use the quantum phase inhibitor to destroy the Na'kuhl sun. Despite the efforts of Kal Dano and a Khitomer Alliance ship to save the star, the Tholians were successful. As a result, the Na'kuhl isolated themselves even more from the outside world in order to rebuild their civilization, after rejecting assistance offered by the Alliance to deal with the disaster.
By the 29th century, the Na'kuhl had acquired the means for time travel, and were a faction in the Temporal Cold War, being against the Temporal Accord. (ENT episode: "Storm Front") A Na'kuhl faction utilized time travel to raid a Carreon ship in 2372 and steal a Deltan time perceptor. (DTI novel: Watching the Clock)
In the alternate timeline that was greatly affected by the Cold War, they became enemies of the Certoss, with the Na'kuhl tampering Earth's history and making Humans a threat to the Certoss, which led to the destruction of Certoss Ajahlan in that timeline's future. This led to some Certoss from that future to travel through time to stop the Na'kuhl and wipe out humanity, even when the war was effectively over in the primary universe and the timeline was restored. (TOS novel: From History's Shadow)
At some point, a Na'kuhl faction contacted the Klingons, and gave some of them knowledge of the future in an attempt to manipulate them into doing their bidding. However, the Klingons rejected this and rebelled against the Na'kuhl. Among the knowledge they had gained was the location of a Doomsday machine, which B'Vat later found in the T'Ong Nebula. (STO - Klingon War mission: "The Doomsday Device")
By the 31st century, the Na'kuhl star had been reignited and Na'kuhl Prime been restored. Captain Gubret served as commanding officer of the Wells-class timeship USS Janeway. Gubret and the Janeway welcomed Leader Tarnh and the NV Salvation home after that ship left the 26th century. (STO short story: "No Profit But The Name")