Grom’thar the Thunderbringer is the eldest living shaman of the magnataur race, and one of their strongest warriors as well. From his home in the Dragonblight, he commands about fifty other magnataur, which is quite an impressive feat. As he continues to gain support, he plans to attack a large civilization — likely the nearby trolls — to force them into servitude.[1] (LoM 127)
Dregmar Runebrand says that Grom'thar commands many clans.
Wrath of the Lich King[]
Killing him and taking his head is the objective of 
[74G3] Wanton Warlord.
Quotes[]
Summoned:
- Grom'thar the Thunderbringer yells: I'll consume your flesh and pick my teeth with your bones!
Death:
- Grom'thar the Thunderbringer yells: You're no magnataur! Where... did you... find... such strength?