There have been many reverse flashes!! yes many!!! for each generation of flash there have been reverse flashes with different names!!
here are some of the opposite flashes that came up as a challenging nemesis of flash!!
1)The Rival (golden age)
He is Dr. Edward Clariss, a professor at the university attended by the Golden Age Flash, Jay Garrick. He believes he has recreated the formula that gave Garrick his speed, which he calls "Velocity 9." He had heard Joan golden age flashes girlfriend) one night talking about how the Flash gave his speed to another student, which helped him get the last formula. He was bitter at the scientific community's rejection of his claims. Although he had become famous for other inventions in Europe, Clariss becomes a criminal. He wore a darker version of Flash's outfit and gave it to several other criminals. The Rival's version of the formula, however, proves to be temporary, and he is defeated and jailed.
2)Professor Zoom (silver age)
Eobard Thawne aka Professor Zoom, Thawne started out as a fan of the Flash. He gained super-speed by replicating the electrochemical bath that gave Barry Allen his powers and undertook surgery to make himself look like Allen. He traveled back in time using the Cosmic Treadmill to meet his hero. However, Thawne becomes mentally unstable upon discovering he is destined to become a villain. Though the true name of the Flash's greatest foe was not known in his time, it was known here. Zoom's mind—already disoriented by the stress of time travel as the Treadmill —had changed over the years. He arrives years after he had intended, while seeking escape by convincing himself that he is Barry Allen. However, his true, more violent nature is eventually revealed. "Barry" attacks Central City in 'revenge' for 'forgetting him', before he is defeated by Wally West, who tricks Zoom into returning to his proper time. Even though Thawne retained no memories of his journey, he felt "betrayed" by Barry and deeply hated him. Thawne began traveling back in time to seek revenge on the Flash, using his knowledge of "history" to his advantage.
For viewers of the CW show "The Flash" the reverse flash they show is professor zoom!!
Yes another zoom,
Hunter Zolomon aka Zoom, After arriving in Keystone City, Hunter Zolomon was hired as a profiler, working with the police in their Department of Metahuman Hostilities. His work put him in constant contact with the Flash (Wally West), and the two became good friends. His insight was critical in solving cases, but he resented being stuck behind a desk.
He was severely injured in an attack by Gorilla Grodd, leaving him paralyzed from the waist down. He asked West to use the time-travelling cosmic treadmill in the Flash Museum to prevent this from occurring. West refused, saying that he could not risk damaging the timestream. Zolomon then broke into the museum and attempted to use the treadmill himself. The resulting explosion destroyed the museum (as well as his remaining sanity) and shifted Hunter's connection to time. He could now alter his personal timeline, giving the effect of super-speed.
and ofcourse kid flashes nemesis we all know from "Young Justice"
Thaddeus Thawne aka InertiaInertia was a clone of Bart Allen. He originally fought Allen when he was Impulse. Later when Bart aged five years after Infinite Crisis and became the Flash, Inertia fought him again. Inertia was responsible for Allen's death and when Wally West returned he took revenge by paralyzing Inertia and putting him in the Flash Museum. During Final Crisis: Rogues' Revenge, he was used by Libra and Zoom to try to get the Rogues to join the new Secret Society. He stole Zoom's powers, called himself Kid Zoom, and was killed by the Rogues, who blamed him for making them kill Bart Allen.