Arachnathid
From WoWWiki
Arachnathids are creatures inhabiting Northrend, resembling scorpions and scorpids. They were encountered by Arthas on his journey to Frozen Throne. Probably related to Nerubians. Arachnathids seem to have complex social structure, similar to that of Nerubians, with Kings and Lords as well as lesser minions (although those may be just names given by travellers to especially big examples of the species)
The Nerubians used them as guardians of Azjol-Nerub in The Frozen Throne.
These creatures have been seen outside of Northrend as Dalaran experiments. Garithos released a wave of them on the Blood Elves as they attempted to flee through the Outland Portal.
