Reverse-Flash

The Reverse-Flash is a name used by several supervillains appearing in American comic books published by DC Comics. Each iteration of the character serves as a foil and an enemy of the Flash.
Characters.
Edward Clariss.
Edward Clariss (also known as the Rival and the Rival Flash) first appeared in "Flash Comics" #104 (February 1949), and was created by John Broome and Joe Kubert.
Publication history.
Edward Clariss first appeared in Jay Garrick's final appearance in "Flash Comics" #104 (February 1949), and was created by John Broome and Joe Kubert as an evil counterpart of Jay Garrick during the Golden Age of Comic Books. He would be revived by Geoff Johns and David Goyer in a story called "Injustice Be Done" from the Justice Society of America comic books through the Modern Age of Comic Books.
Fictional character biography.
Although not called the Reverse-Flash, Dr. Edward Clariss was a professor at the university attended by the Golden Age Flash, and had recreated the formula which was behind Jay Garrick's speed. He hears Joan Williams (Garrick's girlfriend) talking about how the Flash's own speed was given to another student, which helped him develop the formula. Bitter at the scientific community's rejection of his claims, Clariss becomes a criminal. A darker version of the Flash with a mask over his head, he gives the formula to other criminals. The Rival's version of the formula is temporary, and he is captured and jailed (later stories have indicated a possible link between the Clariss formula and the Velocity 9 created by Vandal Savage, but thus far no such link has been conclusively proven).
"JSA" #16 (November 2000) contains a flashback to a battle between the Rival and the Flash several months after the former's first appearance. Now that he has inexplicably regained super-speed, Clariss reaches light speed during the fight and vanishes into the Speed Force. After the Justice Society of America's reformation 50 years later, Johnny Sorrow retrieves Clariss from the Speed Force and invites him to join the Injustice Society. Driven insane in the Speed Force, the Rival races across the country on a killing spree. The Flash realizes that the Rival's path across the country spells out Clariss's name and the final murder victim will be Joan; Jay absorbs the Rival's speed before he can kill Joan.
The Rival returns in "Impulse" #88 (September 2002), posing as Joan's doctor. Now pure speed energy, he possesses fellow Golden Age speedster Max Mercury. After battling Jay and Impulse, Max time-travels to an unknown destination. In "" #4, Max escapes from the Speed Force and is rejuvenated by Wally West's energy; this allows him to return to Earth in a new body. Another Golden Age Reverse-Flash is a robot whose only appearance was in one panel of "The Flash" #134 (February 1998), where he is defeated by Garrick.
Eobard Thawne.
Professor Eobard Thawne first appeared in "The Flash" #139 (September 1963). The archenemy of Barry Allen, he is the first to take on the name Professor Zoom, and oftentimes the Reverse-Flash.
Hunter Zolomon.
Hunter Zolomon (also known as Zoom) first appeared in "The Flash: Secret Files & Origins" #3 (November 2001). The archenemy of Wally West, he is the second supervillain to be called the Reverse-Flash. Unlike all other Reverse-Flashes, he did not gain his super-speed from the Speed Force; due to an accident with the Cosmic Treadmill, Zolomon was essentially 'derailed' from the timeline, allowing him to control the rate at which he moved in time that can make him faster than any speedster.
Thaddeus Thawne.
Thaddeus Thawne (a.k.a. Inertia and later Kid Zoom) first appeared in "Impulse" #51 (August 1999), and was created by Todd DeZago and Mike Wieringo. Another character not called the Reverse-Flash, he is a clone of Bart Allen. Inertia first fought Impulse. When Bart aged five years after "Infinite Crisis" and became the Flash, Inertia fought his genetic template again. Inertia was responsible for Allen's death; Wally West returned, taking revenge by paralyzing Inertia and installing him in the Flash Museum. In "", he was used by Libra and Zoom to try to get the Rogues to join the Secret Society. Inertia stole Zoom's powers, called himself Kid Zoom and was killed by the Rogues, who blamed him for making them kill Bart.
Asked who created Inertia, Ethan van Sciver wrote that he could only accept five percent of the credit; the remaining credit belonged to Mike Wieringo (20 percent), Grant Morrison (25 percent) and Todd DeZago (50 percent). According to van Sciver, Inertia's appearance is an inverted depiction of Impulse.
Inertia initially appeared in "Impulse" #50: "First Fool's" (July 1999), followed by #51: "It's All Relative" (August 1999). His greatest character development was in #53: "Threats" (October 1999). Inertia was not featured again until "Impulse" #62 and #66: "Mercury Falling" (July, November 2000), and again for another five years.
He then began making regular appearances, primarily due to Bart being the Flash. Inertia appeared in "The Flash: The Fastest Man Alive" #5: "Lightning in a Bottle, Part 5" (December 2006). In addition to his "Flash" appearances, he appeared in "Teen Titans" (vol. 3) as part of Titans East, an enemy team, beginning in "Teen Titans" (vol. 3) #43 (January 2007). The storyline concluded with (vol. 3) #46 (April 2007). Gathering the Rogues, he attempted to drain Bart's powers for himself; the plan backfired when Wally returned and Inertia's equipment drained the Speed Force, making the Rogues accidentally beat Bart to death. As Inertia tried to escape, he was captured by Wally who steals his speed, leaving him immobile.
Inertia is primarily a speedster, remaining disconnected from the Speed Force after "Infinite Crisis" and injecting himself with Velocity 9. Although Velocity 9 has been unstable, Deathstroke's new variety seems to have no negative side effects. Inertia briefly shares his powers before his death with Zoom, who lends him his speed to pressure him into becoming a new Kid Flash. As the maddened Kid Zoom, he masters human time streams and reverts Zoom to the powerless Hunter Zolomon before he is killed by the Rogues.
Inertia was later resurrected due to Doctor Manhattan's modifications on the timeline, but is currently trapped in the Speed Force. Inertia tries to stop Barry Allen, Max Mercury, and Jesse Quick from escaping the Speed Force, revealing that Eobard Thawne promised to release him and let him take over Bart Allen's body once the former succeeded in his plans. After Barry tries to appeal and talk sense into him, Inertia stops his attacks and runs off. 
Daniel West.
Daniel "Danny" West first appeared in "The Flash" #0 (November 2012). The younger brother of Iris West, the biological father of Wallace West and the uncle of Wally West.
Tangent Comics.
In DC's Tangent Comics, the Reverse-Flash is an evil, holographic duplicate of her Earth's Flash, Lia Nelson, who was created by a sinister government agency. She was charged with negative ionic energy to disperse the Flash's photon-based form. However, the Flash's light-wave powers outmatched the Reverse-Flash's and the latter was destroyed. This Reverse-Flash appeared in only one issue: "Tangent Comics: The Flash" #1 (December 1997).