Edward Clariss, also known as The Rival, was a professor at the university attended by the Golden Age Flash, Jay Garrick. He believed he had recreated the formula that gave Garrick his speed, and would become the arch-nemesis of the first Flash, Jay Garrick.
Bitter at the rejection of his claims by the scientific community, Clariss became a criminal, wearing a darker version of the Flash's outfit. His version of the formula, however, proved to be temporary, and he was defeated when it was expended. He reappeared a few months later, and in battling the Flash, reached light speed and vanished.
Following the reformation of the Justice Society of America decades later, Clariss was retrieved from the Speed Force by Johnny Sorrow, who invited him to join the new Injustice Society. Now pure speed energy, he possessed Garrick's fellow Golden Age speedster Max Mercury.
Main article: The Rival (Arrowverse)
Actor Todd Lasance portrays an alternate incarnation of The Rival in the third season of the CW TV series The Flash. This version is an inhabitant of the "Flashpoint" timeline created when Barry Allen time-traveled and saved his mother from Eobard Thawne. He is the arch-nemesis of this reality's "Kid Flash" (Wally West).
He has a considerably-different costume from his comic-book counterpart, having an all-black costume with an exposed mouth and an orange lightning bolt on his chest, also leaving red streaks of lightning as he runs, in contrast to the Flash's orange lightning. The red lightning is due to having a "fake" and unnatural connection to the Speed Force.