Overlooker

The Overlooker was a rotund humanoid lifeform, a sophont species from the galaxy's Delta Quadrant. They were members, and appeared in charge of, the Hierarchy interstellar nation-state. 

History
The Hierarchy made first contact with the United Federation of Planets in 2376 when they encountered the starship USS Voyager. Using their advanced surveillance technology, they believed the Doctor's Emergency Command Hologram was genuine. 

Voyager later allied with an Overlooker ship to escape the entrapment of the anomaly. 

In 2410, the Alpha Quadrant Alliance, of which the Federation was a part, established permanent contact with the Hierarchy. The Doctor, working undercover, helped AQA representatives to bring the Hierarchy into the fledgling Delta Alliance, a defensive pact against the resurgent, genocidal Vaadwaur Supremacy. An Overlooker science/intelligence officer applied to join the crew of an AQA vessel. 

Alternate timelines
In an alternate timeline where Voyager remained in the Delta Quadrant and spurred the formation of the Delta Coalition in the 2370s, rescued Overlooker officers joined the Delta Coalition in their defense against the Undine threat, known as "the Scourge". 

In a simulated timeline where Voyager was prevented from reviving the Vaadwaur in the 2370s, the Iconian Empire turned the Overlookers into a servitor race. After providing them with advanced technology, an enigmatic Hierarchy waged a campaign of terror across the quadrant, and the AQA was unable to form the Delta Alliance to counter.