Gan'arg are stunted mo'arg and serve the Burning Legion as engineers. Smart and fast-thinking, the gan'arg make new inventions and delight in using them to further their own purposes.
These stunted mo'arg are very clever, and are often employed as helpers for their larger brethren. Mischievous by nature, they are fond of employing their own hastily-constructed technologies.
In-game their eyes are hidden by their hoods. Only their nose and mouth can be seen.
Thematically the gan'arg seem to have largely been replaced by the wyrmtongues in the Burning Legion hierarchy, with some wyrmtongues even managing the fel cannons in Felsoul Hold. The gan'arg only appear in one place in Legion: from portals spawned under the Sentinax.