Aslan, the Great Lion, is the creator and one true king of the world of Narnia, and generally a figure of all that is good.
Aslan created the world of Narnia in the Earth year 1900. He brought everything –from the creatures, to the landscapes, to the sky and the stars – into being from an empty dark void by singing and roaring. Narnia was made in the image of Aslan’s Country, the “real” Narnia, although it was nothing more than a shadow compared to the latter’s glory. At the creation of Narnia, Aslan also witnessed the writing of the Deep Magic from the Dawn of Time by his father, the Emperor-Over-the-Sea.
As he appears in Narnia, Aslan is a large talking lion who is terrifying, magnificent, and beautiful all at once. Aslan appears different sizes to different people, such that he is always larger than everyone; as people grow, he grows with them. Aslan is very wise, and a powerful force for good, but as Narnians often say, “he’s not a tame lion.” He can be dangerous, and is an unconquerable enemy if angered.
Aslan is the one true king of Narnia; all of its inhabitants have faith in him and obey him absolutely. Generally, Aslan comes to Narnia to aid its leaders and heroes on important missions for external and personal peace, and to protect it from various evils. He watches over Narnia constantly, although he does not choose to solve all of its problems for its inhabitants. Aslan also periodically brings humans from Earth to Narnia, both to help Narnia and to teach them important lessons.
Aslan appeared on half of the Ultima story when Nick and other Society were attack by Plankton and also a battle with pirates in other world's space.
It's unknown yet when he make another appearence again, but some hints, he might join up again with the Ultimawielder in a massive big battle against a powerful Org's member.