The N'rrgal are a race of gelatinous, slug-like aliens first encountered by Sonic and friends during Chapter 8 of Sonic Chronicles: The Dark Brotherhood, when the Cyclone lands on the N'rrgal Colony in Sector Scylla of the Twilight Cage.
Translucent green and semi-liquid, the uncountably numerous N'rrgal inhabit an exceptionally slimy world. Visitors to their colony rarely see anything other than the simple and silent N'rrgal workers - until they start to cause trouble. Individual N'rrgal drones can aggolmerate together in order to produce fearsome warrior opponents. Enough of them in one place allows them to form the N'rrgal Queen, a kind of controlling hive mind that posesses the knowledge of its constituent drones.
The N'rrgal reproduce by mitosis, simply splitting in two to form a pair of new worker drones. Their ability to absorb energy is the N'rrgal's main defense against enemies, as it gives them a powerful regenerative capacity which makes them one of the more infuriating enemies in Sonic Chronicles.
The N'rrgal are sworn enemies of the Zoah, and have warred against them for thousands of years. In Chapter 10, the N'rrgal leech energy from the Nocturne's forcefield defences, enabling Tails to fly the Cyclone inside.