In the beginning...

The Creator created the Wheel of Time, which is time itself. The Creator imprisoned the Dark One outside of the Pattern at the moment of creation. A bore was made into the Dark One's prison, but it was sealed before he entered the world. It is now held closed by seven seals.

Pretty vague, eh? Jordan seems to want to keep the origin of the universe very vague.

According to Ishamael's philosophy (Guide), in each age the Creator and the Dark One have champions who lead their battle for supremacy. These champions are the same two souls who are reborn at the end of each age. The Creator's champion in the Age of Legends was Lews Therin Telamon, the Dragon. In the current age, the champion is the Dragon Reborn, Rand al'Thor. The Dark One's champion in the Age of Legends was Ishamael who was partly trapped with him when the bore was sealed. By all appearances, Ishamael was still the Dark One's champion until his death at the end of The Dragon Reborn. Since that time, the Dark One has tempted several of his minions with the title Nae'blis, but that honor has apparently been bestowed on one of the new Forsaken, Moridin.

At the end of the current age the Creator's champion, the Dragon Reborn, will face the Dark One at the Last Battle, Tarmon Gai'don.

References#

• NS,Ch3 - Hearing Siuan's Foretelling, Moiraine and Siuan know that the Dragon will again face the Dark One at Tarmon Gai'don and break the world.
• NS,Ch8 - Ellid Abareim claims she heard Adelorna tell Shemaen that Gitara had a Foretelling that Tarmon Gai'don will come during the lifetimes of sisters now breathing.
• TSR,Ch9 - Lanfear tells Rand that with the giant statue sa'angreal they could challenge the Great Lord or the Creator.
• TSR,Ch10 - When Rand tries to use Callandor to Heal a dead child, Moiraine tells him to stop because only the Creator can give life.
• TFoH,Ch6 - Seeing the two control statues, Lanfear tells Rand again that they could challenge the Great Lord or the Creator.
• LoC,Prologue - The Great Lord tempts Demandred with the title Nae'blis.
• LoC,Ch6 - Graendal has also been to Shayol Ghul and been promised the title Nae'blis.
• LoC,Ch18 - Herid Fel tells Rand that Tarmon Gai'don will not really be the Last Battle. The Wheel of Time is truly a wheel, so there are many Last Battles. No one can do what the Creator did, yet, when the Second Age comes around again the Dark One's prison must be whole and intact.
• LoC,Ch23 - Graendal now thinks that Sammael may be Nae'blis.
• WH,Ch13 - Moridin is Nae'blis.
• WH,Ch14 - The Seanchan version of the Prophecies of the Dragon says that the Dragon Reborn must kneel before the Crystal Throne before Tarmon Gai'don or all is lost.
• WH,Ch27 - The Borderlanders believe that the Last Battle will be fought in the Blight.
• WH,Ch35 - Cyndane thinks that she would have challenged the Great Lord and the Creator with Lews Therin, but he spurned her.
• WH,Ch35 - Osan'gar thinks that if he kills Rand and takes Callandor he will surely be named Nae'blis.
• CoT,Ch5 - When Perrin passes on the scent of Darkhounds, the wolves tell him that the Last Hunt is coming.
• CoT,Ch8 - Darkhounds and wolves will fight in the Last Battle.
• CoT,Ch24 - Rand thinks about the Creator's plan, then is surprised at himself as this is more typical for Lews Therin.
• CoT,Ch24 - Elza Penfell's logic for protecting Rand is that he must survive to Tarmon Gai'don for the Great Lord to defeat him.
• KoD,Prologue - A faction of the Whitecloaks led by Galad decides that they must fight the Seanchan and Tarmon Gai'don even if it means allying with the Aes Sedai.
• KoD,Prologue - The Aes Sedai sworn to Rand feel that their oaths hold until Tarmon Gai'don.
• KoD,Ch10 - Seanchan lore is that the dead walking is a sign that Tarmon Gai'don is coming.
• KoD,Ch22 - Logain believes that the Creator cleansed saidin , not Rand.
• KoD,Ch22 - Logain orders the Sea Folk to march for Tarmon Gai'don.
• KoD,Ch24 - Ghosts appear and changes occur in the White Tower indicating the nearing of Tarmon Gai'don.
• TGS,Ch5 - Rand hopes that Lews Therinltt will help him figure out how to reseal the Bore.
• TGS,Ch15 - Moridin explains his philosophy to Rand. There is no use in fighting the Dark One. Every time the Dark One fails there will be a new Age but if he wins even once, the Pattern will be destroyed and the Wheel of Time broken forever. Ultimately he must win.
• ToM,Prologue - The Forsaken, at least, believe that what the Creator can create, the Great Lord can destroy.