In the creation myth of the Altmer, 'The Heart of the World,' Xen is mentioned as being one of the spirits who was born of the Aurbis prior to the creation of Mundus. Once Auriel formed and instituted time, Xen gained greater self-understanding and took a name alongside other entities such as Mara and Magnus. Xen later joined other et'Ada in helping Lorkhan to create the mortal plane, but by the time Lorkhan's trick was revealed to the being Xen had already been trapped in Mundus, unable to escape as Magnus had done.
Not much is known about this deity, but the being's name is reminiscent of the names of the Kothri and Bosmeri god Z'en and the Nordic god Tsun. Like these gods, Xen may have been incorporated into the pantheon of the Eight Divines by Saint Alessia as the Imperial deity Zenithar.