The Callieach are an extinct race of powerful magic users.
Not much is known about the Callieach, save for legends of their powerful magics and artifacts. While the Callieach were a frail race, their talent for magic was beyond anything that the wizards of the present day could achieve.
The Callieach were the first to uncover the dream magics from the Wyrd Runestones and soon created a powerful civilisation.
The Trow attacked the Callieach cities and stole the Runestones from them, inciting a war between the two races. The Callieach, despite having god-like magics, were no match for the Trow and their iron weapons.
In a final act of defiance, the last of the Callieach destroyed themselves, along with their Trow pursuers, leaving behind the Great Devoid.
Their sacrifice soon showed that they had an indirect influence in the defeat of Balor, when his severed head was hurled into the Great Devoid, destroying The Leveller forever.
In Irish mythology, a Callieach is a divine hag that can wield powerful elemental magics.