The Bolgar were a species of extra-dimensional beings at war with the Teuthis. They resembled giant amphibians, with thick green skin that seemed to hang loosely off their teardrop-shaped bodies and were covered in slime that dripped to the ground. They had no visible legs, which were hidden by the massive folds of their bodies. They also had four arms, which were jointed in the middle but were also rail-thin. Large swelling bulges and the ends could be considered hands, and half a dozen small, dangling, string-like appendages on each "hand" served as fingers.
Their squat heads had four bulging eyes at the top that blinked in sequence from left to right, four times in quick succession over and over again. The mouth was located at what a humanoid would consider the bottom of the throat. When their language was translated with a universal translator, their voices sounded warbly.
The Bolgar did not have a name for their home realm, believing it to be a symbol of supreme arrogance to think that they would have the right to name it. It would make them look as if they were greater than the realm itself. However, they did name the transwarp conduit that the Teuthis used to enter the primary universe, calling it the Teuthis Corridor. They also did not know what stars were, as their realm did not have any.
They were in constant battle against the genocidal acts of the Teuthis, with both of the races becoming the last inhabitants of their realm as all others died out due to the Teuthis' war campaigns.
In 2379, the Bolgar attempted to form an alliance with Captain Mackenzie Calhoun to help fight the Teuthis. It turned out in the end that the Teuthis were wiped out by the Bolgar and Calhoun. But not long after, the Bolgar started to have delusions of grandeur, making plans to invade the primary universe and take it as their own. But this never came to fruition, as the Bolgar and their dimension were later destroyed by Q and his son while on a "fishing trip". (NF novel: Missing in Action)