Ontailian

The Ontailians were a secretive, non-humanoid race that resided on the planet Ontail in the Rashanar Sector of the Alpha Quadrant.

History
Ontailians established a stable society in the 1400s, and over the next 900 years they developed little beyond small technological advances. In the 1870s, the Ontailians developed space travel and they began to chart the local space around them. In around 1878, they encountered the "demon-flyer", a shape-shifting vessel from another dimension. The Ontailians began to appease the vessel and other the next 500 years the Ontailians and the "demon-flyer" formed a special relationship.

The Ontailians first encountered representatives from the United Federation of Planets in the early 2360s, but the Ontailians expressed little-or-no interest in discovering about Federation cultures, and expressed no desire to become Federation members. This changed in 2374, when Ontail was one of the planets that stood in the way of Dominion forces in the Dominion War against the Federation. Not wanting to be destroyed by the Dominion they were fast tracked to Federation membership, but even then showed no interest in learning about other cultures. Even when Starfleet and Dominion forces were fighting in the Battle of Rashanar nearby, the Ontailians lent little aid to the battle, even when all ships were destroyed they lent little aid.

In 2377, the Federation decided to begin clearning the Rashanar Battle Site and assigned the USS Juno to begin collecting the bodies of the fallen. The Ontailians lent a large force to help with the clearing of the site and to keep looters and scavengers at bay. In 2378, the Ontailians attacked and destroyed the USS Juno after the USS Enterprise (NCC-1701-E) destoyed the Ontailian flagship, Vuxhal, after they believed it to be a duplicate created by a Dominion weapon.

It was later revealed that the Ontailian claim that the Enterprise destroyed the real Vuxhal was destroyed was false, and they were keeping the secret of the "demon-flyer" from their Federation allies. To prevent the truth from coming out, Captain Jean-Luc Picard of the Enterprise agreed to live with the disgrace of his supposed actions, to allow the Ontailians to remain in the Federation.

(TNG novels: A Time to Be Born and A Time to Die).