Ancient Orc Ancestors are ghosts of orcs that walk around Nagrand.
You can only see them after you complete the quest Vision of the Dead in the Levixus the Soul Caller quest chain. They are also used in another quest, a horde only quest, called What the Soul Sees.
Quests[]
[67] Vision of the Dead — from 
Lua error in package.lua at line 80: module 'Module:Factiongfx/faction_tip_link.json' not found. Nitrin the Learned at the Abandoned Armory in Nagrand
- Objective: Nitrin at the Abandoned Armory in Nagrand wants you to bring him:
1x
[Flawless Greater Windroc Beak]
1x
[Mountain Gronn Eyeball]
1x
[Aged Clefthoof Blubber]
[68] What the Soul Sees — from Lua error in package.lua at line 80: module 'Module:Factiongfx/faction_tip_link.json' not found. D'ore at the Auchenai Crypts in Auchindoun
- Objective: Locate a Soul Mirror somewhere in the Auchenai Crypts and use it to call forth a Darkened Spirit from Ancient Orc Ancestors in Nagrand. Destroy 15 Darkened Spirits so that the ancestors may rest in peace.
Return to Mother Kashur at the Ancestral Grounds when this task is complete.
Quotes[]
"What will become of us when it falls?"
"Cannot control... It draws me in... The void grows..."
"I remember everything..."
"The spirits call... I am consumed."
"It is dying. It is dying. It is dying."
"The pain is unbearable."