Many comic book superheroes have a clearly defined arch-nemesis, a villain that stands above the rest of their respective rogues galleries as a clear primary antagonist that serves as a recurring foe to truly be reckoned with. Batman has the Joker, Superman has Lex Luthor, Green Lantern has Sinestro; the major DC Universe heroes have a definitive enemy they will be forever associated with. The distinction is a bit murkier for the Flash, with such an extensive and enduring rogues gallery that it is a bit more difficult to point to one villain specifically as the Scarlet Speedster's greatest enemy.

Now, CBR is breaking down the most prominent villains in the Flash's rogues gallery to find out who is truly the greatest nemesis for DC's Fastest Man Alive.

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Captain Cold

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The oldest villain on this list has endured for decades precisely because of his popularity and longstanding feud against the Flash. Created by John Broome and Carmine Infantino in 1957's Showcase #8, Leonard Snart suffered a particularly unhappy childhood to become the nefarious Captain Cold through use of an experimental cold gun and his own criminal instincts, honed by years of carrying on as a working class criminal.

The de facto leader of the Central City rogues, including fellow themed foes such as Heat Wave, Mirror Master, Weather Wizard, and Trickster, Captain Cold has formed a begrudging sense of respect for Barry Allen and Wally West, engaging them with his own twisted code of honor. While Cold's gun can freeze objects and people to absolute zero, it can also generate a cold field that slows down anything caught in its aura, including the Flash. Appearing in both live-action Flash television series and numerous animated series, Captain Cold is one of the most recognizable Flash villains.

Zoom

The most recent addition to this list is Hunter Zolomon, better known to fans as Zoom, the latest incarnation of the Reverse-Flash who ran against Wally during his tenure as the Scarlet Speedster. Created by Geoff Johns and Scott Kolins in 2002's The Flash: Secret Files & Origins #3, Hunter began as a began police profiler with a tragic past who befriended Wally and the Flash. After being paralyzed by Gorilla Grodd, Hunter begs Wally to alter history by preventing the tragedies in his life only to be rebuffed over concerns of damaging the space-time continuum, effectively ending the two's friendship.

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Hunter sneaks into the Flash Museum, attempting to use the Cosmic Treadmill himself only for it to malfunction and explode, granting him the ability to manipulate time and appear to have super-speed. Rebranding himself as Zoom, Hunter sets out to make the Flash a better hero by inflicting tragedies on Wally's life, including the temporary deaths of Wally and his wife Linda Park's unborn children. Zoom would become a threat for the larger DCU, attempting to make its heroes better provided they survived the ordeal he subjects them to.

Gorilla Grodd

One of the savage and powerful villains in the DCU since the Silver Age has been the hulking, telepathic primate Gorilla Grodd. Created by John Broome and Carmine Infantino in 1959's The Flash #106, Grodd was a typical African gorilla who gained genius-level intelligence after coming into contact with an alien spacecraft that crashed in the jungle. With his fellow intelligent apes, Grodd founds Gorilla City hidden deep in the wild and conquers the city, with plans to take over the entire Earth. The Flash was only able to defeat Grodd after being contacted by the heroic telepathic gorilla Solovar.

After his defeat, Grodd went on to develop a deep hatred for the Flash, often targeting the hero and Central City in revenge for his constant humiliations. Either working alone, with fellow intelligent gorillas, or with the other villains of the DCU, whenever Grodd appears, the Flash drops whatever he's doing to make defeating the simian an absolute priority, knowing the devastation and complete disregard for human life that the villain is capable of. In addition to his heightened strength and powerful telepathic abilities, Grodd has attempted to access the Speed Force several times, giving him bouts of speed matching the Flash on occasion.

Reverse-Flash

Eobard Thawne had started as a scientist in the 25th century that was a fan of Barry Allen to the point of psychotic obsession. Created by John Broome and Carmine Infantino in 1963's The Flash #139, Thawne would recreate the electrochemical accident that gave Barry his powers only to learn that he was destined to become the speedster's greatest villain. His fragile mind broken, Thawne would charge the Negative Speed Force and use the Cosmic Treadmill from the Flash Museum to travel back and confront his former hero in exceedingly deadly battles.

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Thawne murdered Iris West and forced Barry to kill him, and the villain's death and crimes haunted the speedster. After his resurrection during Blackest Night, Thawne would travel even further back in time, causing all the major tragedies in Barry's life including the murder of his mother, framing Barry's father. After Barry caused the Flashpoint reality in an attempt to save her, Thawne would resurface to taunt him, boasting he had become the Flash's greatest foe.

While all of the villains on this list of caused Flash plenty of trouble, the Reverse-Flash is the only one who damaged the Flash's life, and the DC Universe, so irreparably. Thawne fundamentally changed Barry Allen's origin decades after the hero's creation on a scale that's otherwise unheard of in superhero comics. The Reverse-Flash might boast about being Flash's greatest enemy, but he does so with good reason.