The Borg Queen was the name given to the entity that existed within and served as a central nexus for the Borg Collective. The name was given to her by the Federation scientists Magnus and Erin Hansen, who discovered her existence. She was part of the Borg-Horde War
The Borg Queen was assimilated to the Collective around the age of 7-8 and was already present in the entire timeline. The Queen defined herself as, "I am the beginning, the end, the one who is many. I am the Borg." Although this suggested she was an individual within the Collective, while addressing Borg drones as "my drones", she was not an individual. The purpose of the Queen was to bring order to chaos.
The Borg Queen was a humanoid female of Species 125. In accordance with the Borg pursuit of perfection, a blending of the organic and synthetic, very little of her original humanoid form remained. Her face and upper torso were organic while the rest of her body, including her skull and spinal cord, were synthetic. Because of her disembodiment she saw herself as the epitome of perfection. The Queen had her own chambers within the Borg Unicomplex from which she could oversee and control the Borg via command interface.