From WoWWiki

Leaders: Rend Blackhand and Maim Blackhand

Clan Colors: Black

Domains: Blackrock Spire, Black Morass

The Black Tooth Grin Clan was originally part of the Blackrock Clan but after Blackhand was deposed as Warchief, his sons Rend and Maim sought to establish their own power base within the Horde. Rend and Maim, leaders of the clan, were also the ones who assassinated the parents of the New Horde's Warchief Thrall on the orders of Gul'dan. During the Second War, the Black Tooth Grin was responsible for guarding the Dark Portal and fought on the front lines during the campaign for Khaz Modan. The clan receives its name from the tradition that every recruit must knock out one of their own teeth to show their loyalty.^{W2Man 70}

Side Note: "Black Tooth Grin" was also a phrase sang by Dave Mustaine in a song for the popular metal band Megadeth. The phrase became popular after Pantera guitarist and prodigy "Dimebag" Darell Abbot created an alcoholic drink named the "Black Tooth Grin" and even tattooed the phrase on his leg.

Known members:

Name	Location
Rend Blackhand	Hall of Blackhand,	Blackrock Spire
Maim Blackhand	Deceased

Orcish Clans of the Second War
Clans and Leaders	Black Tooth Grin	Blackrock	Bleeding Hollow	Bonechewer	Burning Blade
	Rend / Maim	Blackhand / Orgrim Doomhammer	Kilrogg Deadeye	Tagar Spinebreaker	None
Clans and Leaders	Dragonmaw	Frostwolf	Laughing Skull	Shadowmoon	Shattered Hand
	Zuluhed the Whacked	Durotan	Mogor the Ogre	Ner'zhul	Kargath Bladefist
Clans and Leaders	Stormreaver	Thunderlord	Twilight's Hammer	Warsong
	Gul'dan	Fenris the Hunter	Cho'gall	Grommash Hellscream