The Thallonians were a humanoid species native to the planet Thallon located in the Beta Quadrant. For centuries, the Thallonians were the dominant species in the Thallonian Empire which controlled much of Sector 221-G. Following the collapse of the Empire and destruction of Thallon in 2373, the Thallonians were forced to become refugees, seeking homes with their former subjects until the establishment of the New Thallonian Protectorate on the planet New Thallon circa 2378. They are a dark red skinned people with protruding brows, small eyes and arched eyebrows. Some Thallonians had joined Starfleet by 2377, such as Jang Si Naran, who serves aboard Deep Space 9.
The Thallonians are referred to as The New Ones by the Priatians.