The Endless are 7 spirits created by the God of Requiem, A'llye, created to fulfil certain roles within the Real of the Living. These seven spirits (destiny, death, despair, delirium, desire, destruction and dream) will enter a newborn child and carry out their role as an Endless subconsciously (usually in their dreams).
When an Endless becomes "awakened" they can choose whether or not they wish to carry out their role. With the exception of Death, when an Endless dies, they will simply be reincarnated with their memories being sealed away until they are awakened.
Authority of Death: Subconsciously capable of travelling between all 3 plains of existence and having a dominion regarding what happens to a soul when it's host dies and it becomes a spirit.
Awakening: As one of the seven Endless, inconceivably powerful beings, Death is both lord and personification of all death and life, Death meets with the recently deceased and guides them into their new existence. He also visits people as they are born. Evidently, only he seems to remember these encounters.
Gift of Death: Death has the power to free the soul of a body and send a soul to his appropriate destination (usually an afterlife or reincarnation).
Gift of Life: Death apparently is also there at the time of ones birth and can infuse a body with life.
Authority of Dream: Subconsciously, Dream can effortlessly travel across the "Dream Dimension", meaning she can enter the minds of others and grant them visions, through their dreams.
Awakening: As one of the seven Endless, inconceivably powerful beings, Dream is both the lord and personification of all dreams and stories, and all that is not in reality (which, in turn, Dream may define by his existence). He possesses absolute control over sleep, dreams, nightmares, and even insomnia.
Dream Reality Warping: Inside the Dreaming, she can effortlessly alter reality on a universal scale. She can create objects and entities to follow his every command. The Dream's landscape and weather can also change simply by her current mood, and she also controls all the dreams within it.
Dream Conjuring: She is capable of summoning dreams, stories, and ideas and send them into the minds of others.
Authority of Destruction: Subconsciously, Destruction can witness all the violence going on around the universe.
Awakening: One of the seven Endless, inconceivably powerful beings, Destruction is both lord and personification of all Destruction and Creation. He has power over the action and process of destroying as well as the act of making, inventing, or producing.
Authority of Desire: The Endless of Desire is born with the drive to achieve whatever they want, an indomitable will that simply will not budge under any circumstance.
Awakening: One of the seven Endless, inconceivably powerful beings, Desire is both lord and personification of all desire and fulfillment, she has god-like powers and absolute power over its realm. She has power over craving of the unattainable. The force of physical appetite or emotional need. Strong envious desire. In contrast it is also lord over satisfaction, extending to the attainment of ones desire. Desire has also been said to be able to manipulate the desire of others.