Only mentioned in The Desert Spear by a mind Demon as "The Queen" it can be assumed that she is the supreme ruler of all demon kind. She is known to the Krasian's as Alagi'ting Ka the mother of all demons.
It is revealed in "The Daylight War" that the current queen is the most powerful of all demons and rules the mind court. She lays eggs form her egg sack that is then imprinted by a mind demon it is unknow if this will make the eggs hatch into other Mind Demons or into lesser demon. It is also unknown if she lays the eggs for all demon kind or only mind demons as it is thats she is "Bloated with eggs" so the exact number is unknown.
It is not the first queen. It is hinted by the Royal Consort that the last queen was either killed or died as it stated that "She was not alive then" This also implies that the queen is around three thousand years old, as she was born close to the end of the last demon War.