Flash, the wise-cracking speedster of the DC universe, is one of the most popular – and powerful – comics superheroes of all time.
Much like Batman and Green Lantern, Flash is a legacy character, meaning that there’s more than one person to have filled the role.
However, it’s the Barry Allen version of the character that’s had the most impact, both in the comics and in the real world. In the comics, Barry’s inherent connection to the powerful and mysterious ‘speed force’ means that, much like Marvel’s Scarlet Witch, he’s often been used by writers to reset the universe – or even create a temporary universe so that the writers can deconstruct their characters.
Outside of the comics, the Barry Allen of the 90s ‘The Flash’ TV series was arguably responsible for the acceptance of live-action versions of DC comic book characters into the mainstream. While the same could be said of ‘Lois and Clark: The New Adventures of Superman’, The Flash (somewhat aptly) arrived on the small screen 3 years earlier than the Superman-themed workplace rom-com.
This would be followed by Smallville in the early 2000s, right up to today’s CW Arrowverse – which also features a Flash TV series.

Flash: Real-world origins
Jay Garrick, the first Flash, was created in the late 1930s by writer Gardner Fox and artist Harry Lampert.
Flash’s character design was loosely based on the appearance of the Roman God of travel, Mercury. This is why the first Flash had a winged helmet and winged footwear. This, in turn, is why most of the Flash-allied speedsters have small wings on their headgear.

He first appeared in Flash Comics #1, which was an anthology comic (meaning it contained multiple unrelated short stories in comic form). Before long, the first Flash was given his own solo series, the aptly named All-Flash.
Comics would sadly become much less popular after World War II, and so Garrick’s first (and only) solo series would be cancelled, and the character would disappear for almost two decades.
DC rebooted the Flash character in the mid 1950s, replacing everything about him apart from his powerset. This version was, of course, the ‘Barry Allen’ Flash. Jay Garrick’s version of the Flash would still exist, but only as a fictional comic character within the DC universe. Barry Allen was soon given a sidekick, a fellow speedster known as Kid Flash (Wally West).
In the early 1960s, the two versions of Flash would meet in The Flash #123 during the groundbreaking story titled ‘Flash of Two Worlds!’, thereby introducing the concept of the multiverse (multiple universes) to DC Comics.
Eventually, in the mid-1980s, DC comics would decide to merge all the different universes together in the first of their many reboots. This was the landmark crossover event known as Crisis On Infinite Earths, and its storyline would sadly see Barry Allen’s Flash heroically sacrifice himself so that others could live. Unbeknownst to the rest of the universe, he wasn’t actually dead – just trapped by the speed force.
Barry’s sidekick, Kid Flash, then took up the mantle of the Flash.
The majority of the Wally West Flash stories began with Flash saying ‘I’m Wally West, and I’m the fastest man alive’. This quote is often referred to by the CW version of the Flash.
It raises an interesting question. Who is the quicker speedster: Garrick, Allen, or West?
Canonically, the answer is actually Wally West.
However, during yet another DC universe reboot, Barry Allen returns. Like Allen before him, Wally West would now be the one trapped by the speed force.
Flash would also cause another DC universe reboot when he used the speed force to travel back in time and save his mother, accidentally creating the iconic Flashpoint universe. The Flashpoint universe was notable due to most DC characters having a much darker and grittier presence, but Flash would soon set things right again.

Flash: In-universe origins
Barry Allen was a young man who enjoyed lazing around and reading comics.
His favourite comic superhero was a speedster named ‘Flash’, and Allen often fantasised about being the Flash himself.
When he grew up, he was a forensic scientist working for the Central City Police Department. One night, while working late, a bolt of lightning hit him and knocked him into a shelf full of chemicals, knocking him out. When he came to, he found that the mixture of electricity and chemicals had given him the superspeed he’d wished for in his youth. Inspired by his favourite comic superhero, he took the name Flash and began fighting crime as a costumed superhero.
Not long after this, the Earth would be attacked by an alien invasion force. All the major superheroes of Earth banded together to defeat the invading army, which they succeeded in doing. Deciding on the spot to form an official alliance, the heroes formed the Justice League.
He would find time among all his adventures to marry the love of his life, Iris West.
His nephew, a teen named Wally West, would also gain superspeed in a manner quite similar to Allen himself. Wally would become the costumed sidekick, Kid Flash.
Allen would eventually find himself somehow transported to an alternate reality, a reality in which Jay Garrick (his childhood hero) was the Flash (and not just a fictional comic character). Working together, they were not only able to work out how to get Allen back home, but also how to travel between the two universes when required.

Allen also once visited our universe, and spoke to Flash editor, Julius Schwarz.
He must have irritated Schwarz, because his next few years were a living hell.
Iris is killed by a speedster villain named Professor Zoom. Flash avenges his dead wife by killing Zoom. Another villain (posing as a speedster named Reverse-Flash) then begins to attack him relentlessly, but Allen also defeats him.
Broken of heart and spirit, Flash uses his connection to the speed force to travel to the 30th century, having learned that Iris’ spirit had retreated to that time period. Reunited, the couple lived happily together for a short while.
However, a cosmic entity known as the Anti-Monitor had been watching the whole thing, and wanted to put the universe back how it was before, so that all of the multiple universes could be merged into one. Sadly, Barry seemed to have perished battling the Anti-Monitor, so it fell to Kid Flash to take the mantle of the Flash.

However, Barry wasn’t dead – just stuck in time, trapped as pure energy like some kind of living lightning bolt.
Trying to get back to his own universe, Barry appeared in a police lab somewhere in his own past. Surprised by this, Barry’s concentration lapsed for a spilt second, and he accidentally knocked his former self onto a shelf full of chemicals – he’d been the bolt of lightning which had hit him all those years ago!
Allen would eventually get back to his own time, and go on even more bizarre adventures, but this is the perfect place to end Barry’s story – his actions had caused him to give himself the powers which had caused him to give himself the powers which had caused him to give himself-
Well, you get the idea.