A Silithid Colossus
A Silithid Colossus is a huge creature with brutal strength and attack with great strength. In each Hive of Silithus sleeps one, awaiting battle.
After the Scarab Gong was rung and the ancient Gates of Ahn'Qiraj opened, the the horrors of the Silithid and their Qiraji masters were revealed. Massive Qiraji Resonating Crystals broke through the earthen crust of Kalimdor and the Colossus of the Hives in Silithus broke free of their cocoons beneath the Hives. They heard the call to battle and rose to serve their masters. They cast their massive shadow upon the whole of Silithus and marched into war.
It is possilble that more of those beasts are in Ahn'Qiraj.