1) Jay Garrick
The very first person to call himself The Flash was Jay Garrick, who appeared in Flash Comics #1 in 1940. He was a college student prior who accidentally inhales hard water vapors in his laboratory after taking a smoke break, giving him super speed and reflexes.
After a brief college football career, he decides to don a costume and fight crime. He takes his father’s helmet from World War I and fashions wings on it in the style of the Roman God Mercury, often depicted with a winged helmet and sandals. Donning jeans and a red shirt with the lightning bolt fashioned on it, he would later go on to become a founding member of the Justice Society of America and its first chairman.
This first version of The Flash would be the best known of the so-called “Golden Age” of comics. Unfortunately, after World War II, superheroes faded from popularity and so did the Jay Garrick version of The Flash. By 1951, all comics with this version of the character had been cancelled and he wouldn’t return to for another ten years, and even then not in a solo series.
To explain the existence of multiple versions of not only The Flash, but other DC comic book heroes, parallel worlds were invented in which multiple versions of Earth contained different characters. Garrick’s Flash exists on Earth-2, while the Barry Allen version exists on Earth-1. The wormhole created in the finale of The Flash television show opened up the possibilities for crossing between worlds and was furthermore confirmed when we saw the winged metal helmet show up in Barry’s world.