From the Tal'Dorei Reborn Campaign Setting.

Those who travel through the Parchwood Timberlands sometimes hear thunder roll through the valley, accompanied by the cracking of timbers, but no storm follows. Over twenty years ago, the Briarwoods slaughtered and reanimated an entire clan of giants native to the Parchwood. Most of these zombie giants have been destroyed by the Grey Hunters, but few still remain. However, their mindless actions are not without purpose: each giant is tormented by being denied the halls of their ancestors, and quietly weeps for their lost afterlife as they roam.