Rival

Rival is one of the oldest villains of Flash, first fighting Jay Garrick near the beginning of his career. He was a teacher who found out Garrick's connection to the Speed Force came from chemicals, a "hard water" formula. He attempted to duplicate it, and made a formula that would temporarily give him Garrick's power. He used it and nearly killed Jay-but it ran out and he was arrested. He was using the name "Rival". Later, Rival returned with the formula, and ran so fast he broke light. He then vanished into the Speed Force. Decades later, Rival reappeared. He had been trapped in the Speed Force for 50 years before Johnny Sorrow freed him. Since his powers were temporary, the Speed Force ate away at him and drove him insane. He went on a killing and crime spree looking for Jay Garrick, who defeated him by absorbing his connection to the Speed Force. Rival kept gaining speed and became pure energy, and he recently took Max Mercury's body and vanished into time.