Zoom
Hunter Zolomon came to Central City with a tragic past - a serial killer father, a failed career as an FBI agent, and a failed marriage. Working as a police profiler, Hunter found peace helping the Wally West Flash and the police - until Gorilla Grodd snapped his spine and left him crippled. Bitter and angry, Hunter asked the Flash to change the timestream and prevent this latest tragedy from happening. The Flash refused, so Hunter tried to use a time travel device by himself. Hunter's attempt ended with the device blowing up in his face.
The accident removed Hunter from the timestream, allowing him to move through time like he had super-speed. His sanity now fractured, Hunter decided that in order for the Flash to become a better hero, he must understand tragedy. So Hunter became the super-villain Zoom, patterned after the original Reverse-Flash. Zoom battled the Flash repeatedly, torturing the hero while repeatedly saying that this was to make him a better hero.