Dark Flash

Bartholomew Henry "Barry" Allen was a future version of Barry Allen after many repeated attempts to prevent the death of his Justice League friends, turning into a dark being named Dark Flash. Barry received his powers from his Earth-1 counterpart, and reveals that he purposefully pushed Earth-1 Barry out of the Speed Force to ensure his creation. He waits patiently inside the Speed Force until Earth-1 Barry and his past self enter the Chronobowl, where his past self starts resetting the timeline over and over in the hopes of saving Supergirl and Batman, starting the loop that will transform him into Dark Flash. Dark Flash reveals to Earth-1 Barry and his past counterpart that he is his future self, and has figured out that killing Earth-1 Barry will allow him to finally save them and win the fight against Zod. However, his past version realizes this and sacrifices himself to save Earth-1 Barry, which leads to him being erased from existence.