The Flash
The original Flash was, in the context of the new version, merely a comic book character, by claiming the old stories had entered his subconscious in the form of vibrations from an alternate world, where the character's adventures were real. Once he was established, superheroes began to regain their prominence in the comic book scene. The new Flash also got his super speed in a chemical accident but, in a slight twist, was inspired to become a superhero by having read Flash Comics years earlier.
Editor Julius Schwartz took on the project with the stipulation that the character be re-built from the ground up. In 1956, DC tried reviving the superhero genre, starting with The Flash. By that time, All-Flash was long gone, and Comic Cavalcade had dropped the superheroes and begun featuring Nutsy Squirrel,The Fox & the Crow, and other funny animal characters. The superhero trend eventually ran its course, and Flash Comics was retired with its 104th issue, dated Feb., 1949.
The solution was to call his solo book All-Flash. In 1942, he joined Green Lantern and Wonder Woman in headlining Comic Cavalcade, an extra-big comic reserved for extra-popular characters. He thereupon made himself a costume and embarked on a crime-fighting career as The Flash. Jay Garrick, college student, had an accident in a chem lab, inhaled fumes that would undoubtedly be deadly anywhere but in a superhero comic book, and fell unconscious. The Flash had a straightforward superhero origin, written by Gardner Fox and drawn by Harry Lampert. There was even a funny animal speedster and The Terrific Whatzit actually wore a duplicate of The Flash's own costume. They include The Whizzer, from the company that would later be known as Marvel;Quicksilver, from Quality Comics ; and DC's own Johnny Quick, a back-up series in More Fun and Adventure Comics from 1941-54.
And he became the progenitor of an entire genre of speedy superheroes, as, within months, his imitators started hitting the stands. He was an early jumper onto the superhero bandwagon Superman himself had been around less than two years. He shared this anthology title with Hawkman,Johnny Thunder, and several other debuting stars.
He took over the mantle of the Flash from his deceased uncle Barry Allen. The third Flash Wally West started his career as Kid Flash working with the Teen Titans. Sadly Barry Allen died in the Crisis on Infinite Earths storyline in the 1980's. He mentored the current Flash, Wally West, his nephew who gained his powers in a freak accident that recreated the first one that gave Barry Allen his powers. The second Flash Barry Allen, a police scientist acquired super speed by being struck by lightning and being bathed with the chemicals he used for work. He is currently active with the JSA and mentors the new Speedster Impulse.
He remains relatively youthful do to an accident that bathed the JSA including Jay's wife in rejuvenating rays.