Primordus

Primordus was the first of the Ancient Dragons to awaken in Tyria. Primordus begins to summon an army deep below Tyria after the destruction of The Great Destroyer. After Primordus's awakening, the other ancient dragons began to awaken one by one.

Primordus in Guild Wars
Primordus can be seen in the final mission in Guild Wars: Eye of the North. He would be the giant statute that looms over the Great Destroyer boss.