Flash (Barry Allen)
After defeats by various heroes, including the Flash (Barry Allen) and Supergirl sacrificing themselves to destroy an anti-matter cannon and to save Superman, respectively, the Anti-Monitor absorbed the entirety of the anti-matter universe and traveled to the beginning of time, intending to stop the formation of the positive matter Multiverse and to create a Multiverse where anti-matter prevailed. When the heroes followed him there, he began to drain the power from most of them.