Adversary
A fragment of the Nameless, broken off as a "backup plan" in case the Dawn War failed (which it did). Contained much of the Awakener thought-form that prompted the war in the first place. Originally summoned back into reality by Aelvar mages of the mid-Second Age in a (mistaken) attempt to draw power from it, it was imprisoned between the timelines by a concerted (and fatal) sacrifice of aelves, celestials, devils, dragons, and giants. There it sat for millennia, although its influence leaked into reality and twisted many timelines. The seal was broken by an Archmagistrate of Kel'tan in about 246 AC, causing the Reweaving. Finally terminally defeated and destroyed by an alliance led by Tempus Machina in late 251 AC.
Of note, the shell of the entity was the Broken Concept of Hope, now warped into Despair with the Nameless fragment and Awakener poison locked inside. When Tempus Machina smashed Namebreaker into that core, Hope was purified and returned to the realm. The Awakener influence was also freed of its bonds to that Outside entity, becoming part of the Dream itself.