In Michael Ende's complex fantasy novel The Neverending Story, the Child Like Empress is an enigmatic figure that drives the plot of the book, although very little is said about her directly.
She rules the magical world of Fantasia, although she does not actually do this through any form of government. In fact, it says many times throughout the book that she does not discriminate between the good and the evil in Fantasia, but merely accepts all around her. And although she physically looks like she is still a girl, she is actually ancient. And no one can see her more then one time.
Her seal is the mysterious Auryn, a double Ouroboros. This seal gives the wearer the power to create anything they wish.
The plot of the book in both parts concerns her, although possibly in the first more then the second. During the first part of the book, the Child Like Empress is sick with a disease that mirrors the destruction of Fantasia by the Nothingness. It is up to Atreyu, with the help of the Auryn, to save her by finding someone outside of Fantasia to heal her by giving her a new name. This person is the person reading the book, named Bastian Balthazar Bux. Through reading the book, he comes to be part of it, and therefore is able to give the Empress her new name, Moon Child.
When he does this, the nothingness destroying Fantasia is stopped, although only a single grain of Fantasia is left. From this single grain, Bastian recreates all of Fantasia using the power of Auryn that the Empress grants him.
Eventually, by using all his wishes, Bastian loses his identity and tries to depose the Child Like Empress and become the emperor of Fantasia. During this time, the Empress does nothing to stop him, but refuses to see him again, since she can see people only once.
Eventually Bastian learns that many other people had visited Fantasia from his world before, and that all had tried to become emperor of Fantasia, and gone insane as a result. He therefore gives up his dream and heads back to his own world.
The role of the Child Like Empress is rather enigmatic. Her personality is undeveloped, although it is hard to say what type of personality an unmoving, symbolic empress of a fantasy land should have. It is also not hinted at what level of insight or control she has over the world around her. Part of the problem, I think, is that if there is some kind of cosmological belief system that Michael Ende believes in, or modelled his work after, it is unknown to me. It could be, perhaps, that Michael Ende developed the imagery and descriptions of his character quite apart from thinking "where they fit in" in a larger sense.
People with a Freudian or psychological bent could probably say something about Michael painting the ideal female chacter in the book as being a beautiful, ancient and wise, yet physically immature woman. In fact, I am sure that more then half a case could be made that this was a little perverted. However, on the whole, I don't subscribe to this, because the imagery and air of the book was so far above a typical psychological mindstate. In other words, the characters should be viewed (if at all) as cosmic archetypes, and not suppressed desires.
Lastly, in the movie, the Childlike Empress is portrayed by a woman named Tami Stronach, who only acted in this one role, before quitting acting and eventually becoming a professional dancer.