3. He Once Broke Reality
One fateful day, Barry Allen decided to travel back in time to stop the Reverse-Flash from murdering his mother. The Speed Force required to do that ended up breaking time though, and the world was left in a devastating state. Bruce Wayne was killed instead of his parents, Superman spent his life locked in an underground military bunker, and Aquaman and Wonder Woman destroyed continents in their war against each other. When Reverse-Flash was eventually stopped, Barry managed to fix time, but this created a new DC Universe which led to the comic book publisher rebooting all of their titles in 2011's "The New 52".