The Flash first appeared in Flash Comics #1 (1940), created by writer Gardner Fox and artist Harry Lampert.
Following the success of Superman, many superheroes start sprouting out on comic books. Most mimicking that of a superhuman strength very much alike to the Big Blue, but some chose to deviate, like The original Flash, whom possesses superhuman speed and superhuman reflexes.
Dubbed as the "Scarlet Speedster", the Flash character was represented by several fictional persons, depicted as from different Earths.
Jason Peter Garrick (aka Jay Garrick) is a college student prior to 1940 (later retconned to 1938) who accidentally inhales hard water vapors after taking a smoke break in his laboratory where he had been working.
As a result, he finds that he can run at superhuman speed and has similarly fast reflexes.
After a brief career as a college football star, he dons a red shirt with a lightning bolt and a stylized metal helmet with wings (based on images of the Roman god Mercury) then begins to fight crime as the Flash. The helmet belonged to Jay's father, Joseph, who fought during World War.
The Flash soon became one of the best-known of the Golden Age of superheroes. He was a founding member of the Justice Society of America and served as its first chairman.
Barry Allen first appeared in Showcase #4 (1956) created by writer Robert Kanigher and penciler Carmine Infantino. His name is actually the combination of talk show hosts Barry Gray and Steve Allen.
For this version of Flash, he wears a distinct red and gold costume treated to resist friction and wind resistance, traditionally storing the costume compressed inside a ring.
Barry Allen is a police scientist with a reputation for being very slow, and frequently late, which frustrates his fiancee, Iris West, as the result of his devotion to crime-solving. One night, as he is preparing to leave work, a lightning bolt shatters a case full of chemicals and spills all over Allen. As a result, Allen finds that he can run extremely fast and has matching reflexes.
The Flash joins the Justice League eventually, and became close friends with Hal Jordan of the Green Lantern.
During Crisis on Infinite Earths, Allen foils a villian's plan to destroy the Earth with an anti-matter cannon, creating a speed vortex to draw the power in, but dies in the process as the power becomes too much for his body.
Wally West first appeared as the Kid Flash in the Flash #110 in 1959. Wally took up the mantle of the Flash following the death of Barry Allen.
Created by John Broome and Carmine Infantino, Wally was depicted as the nephew of Iris West. During a visit to the Central City police laboratory where Barry Allen worked, the freak accident that gave Allen his powers repeated itself, bathing West in electrically-charged chemicals. Wally had a strained relationship with his own parents and often looked to his beloved aunt and uncle for moral support and guidance.
Bart Allen made his first cameo appearance on Flash #91 in 1994 as the superhero Impulse, which was a name given by the Batman much like a warning then a compliment.
Unlike the rest of the Flash, Bart is suffering from a hyper-accelerated metabolism, Bart Allen was aging at a faster rate than that of any other human being, thus causing him to appear the age of twelve when he was chronologically only two years old. To prevent him from developing mental health problems, he was raised in a virtual reality machine which created a simulated world that kept pace with his own scale of time. When it became clear that this method was not helping, his grandmother, Iris Allen, took him back in time to the present where The Flash, Wally West, tricked Bart into a race around the world. By forcing Bart into an extreme burst of speed, Wally managed to shock his hyper metabolism back to normal. Because he had spent the majority of his childhood in a simulated world, Bart had no concept of danger and was prone to leaping before he looked. The youth proved to be more trouble than Wally could handle, and he was palmed off onto retired superhero speedster Max Mercury, who moved Bart to the fictitious Manchester, Alabama.
He joins the Teen Titans at a later stage, and shortly after, he was shot in the knee by Deathstroke. While recovering, Bart reinvented himself to be the new Kid Flash.