Chaos entity
The chaos entity was an intelligent species which lived in chaotic space. They existed on a perceptual wavelength which was undetectable to most humanoid senses. 

In 2375, Chakotay, who had the gene for a cognitive disorder, detected the chaos entities presence as the  traveled through the space they lived in. After communication was established, with Chakotay acting as a liaison, the entities helped the crew of the Voyager in escaping chaotic space. ()

Unnamed species
Memory Alpha articles named from supplementary resources