As a key piece of The CW network's lineup, The Flash has lasted far longer than its first attempt on the small screen, which was on CBS in 1990 for only one season. The inspiration for both shows has been a legacy character for DC Comics since Flash Comics #1 in January 1940. The first Flash, Jay Garrick, headlined his own title and was a founder of the Justice Society of America, but faded from view at the end of the decade, along with most superheroes. But built into the The Flash character is reinvention. When DC revived its lineup at the dawn of the Silver Age, readers got a new Flash, named Barry Allen. This Flash had a new origin, a different supporting cast, more powerful abilities and a cool costume that he keeps in a ring.

For television, The Flash has an extensive history to draw upon. But bringing the character from the page to the screen has its challenges. It necessarily means making a show that plays to the strengths of the different medium. And that has meant that not every element of the show has a one-to-one analogue in the comics. Some aspects of The Flash are unique to the series and haven't been part of any incarnation. Lots of things on the show are the same-but-different. Some things aren't the same at all. Most have been to the good, making for an entertaining show that supports the Arrowverse, but there has been at least one major misstep. Here are the 19 biggest changes The CW made to The Flash -- and one that is unforgivable.

20 A DIFFERENT ORIGIN

The Flash -- Barry Allen in particle accelerator explosion

Barry Allen gets his speed powers in the Arrow Season 2 episode "Three Ghosts." Barry is visiting Starling City to help Green Arrow on a case and to find evidence that will exonerate his father. After he returns to Central City, he is working in his lab. Across town, STAR Labs is launching its particle accelerator. However, it malfunctions and explodes, sending a wave of energy for miles around. A jolt of electricity from the blast strikes Barry, who falls into a shelf full of chemicals.

This is a more elaborate version of The Flash's origin. In Showcase #4 (October 1956), Barry is in his lab and the electrical discharge is a completely random weather phenomenon.

19 THE BIG BANG

The Flash -- particle accelerator explosion

That particle accelerator explosion did more than just jump start Barry Allen's metabolism. Numerous people within the blast radius -- as many as 2,600, according to Season 4 villain Clifford DeVoe, the Thinker -- were affected by particles and by Dark Matter. This caused them to develop the metagene and exhibit metahuman powers and abilities.

Some of the people who were transformed as a result used their new powers for good, like Vibe, Black Canary and Jefferson Jackson, who became part of Firestorm. Unfortunately, many did not. Among the people affected by the particle accelerator were Peek-a-Boo, the Weather Wizard, the Pied Piper, the Ray, Multiplex, Chroma, the Mist, Mirror Master and the Thinker.

18 MORE DIVERSITY

The Flash -- Wally West, Cecile Horton, Joe West, Iris West

Iris West has been part of The Flash since that first story in Showcase #4. But casting Candice Patton as Iris changed the character into an African-American woman. It took some time to win over a subset of fans, Patton told The Washington Post. "I think it was [surprising] when I got the role and understood that a lot of people weren't happy with it. .... Now, it's just kind of set in stone that I'm Iris West."

Another Black actress, Kiersey Clemons, was cast as Iris for the upcoming DC Extended Universe film Flashpoint. Patton told the Post, "If my casting wasn't working, they would have changed it for the film. Generations after this will remember Iris West as Black, whether that's me, or someone else playing [the role] in the film. It's a great thing."

17 IRIS ISN'T FROM THE FUTURE

Iris West Candace Patton Flash

In the comics, Iris West grew up as the daughter of Ira and Nadine West. But it was revealed in The Flash (Volume 1) #203 (February 1971) that she was born in the year 2970. Her biological parents, Eric and Fran Russell, sent Iris to the past to protect her from a pending nuclear attack. In the 20th century, the Wests had recently lost their own infant girl, and Nadine was recuperating. When baby Iris materialized before them, they resolved to raise her as theirs.

For television, Iris's backstory is far simpler: She is the daughter of Joe, a Central City Police detective, and Francine West. Francine was out of Iris's life for much of her childhood because she developed a drug addiction.

16 JOE WEST IS A NEW CHARACTER

Joe West

The 2009 The Flash: Rebirth limited series (April 2009-February 2010) returned The Flash to the DC Universe after his sacrifice in Crisis on Infinite Earths #8 (November 1985). Rebirth altered The Flash's backstory, revealing that during his absence, his father Henry was in prison, framed for the death of his mother Nora.

The TV series adapted that story, but had the incident occur when Barry was 11 years old. Without a mother and with an incarcerated father, Barry would have gone into foster care. But Central City Police Detective Joe West, a friend and neighbor to the Allens, took Barry in and became his foster father.

15 WALLY IS IRIS'S BROTHER

Flash season 4 Iris Wally

In The Flash (Volume 1) #110 (December 1959), Iris West brings her teenage nephew to Barry Allen's apartment, hoping Barry can introduce the boy to The Flash. Iris had yet to learn that Barry himself was The Flash. But on The Flash TV series, Wally isn't Iris's nephew; he's the brother she grew up not knowing about.

He first appeared in the Season 3 episode "Running to Stand Still." It was revealed that Joe West's estranged wife Francine had Wally after she left the family to deal with her drug addiction. Wally grew up in Keystone City, not knowing his father or that he had a sister. He connected with them after an ill Francine returned to Central City to make amends.

14 WALLY GETS HIS POWERS DIFFERENTLY

Wally West as Kid Flash on The Flash.

The story in The Flash #110 that introduces Wally has The Flash show him how he became a speedster. They visit Barry's apartment, which has shelves with an assortment of chemicals like the one he had in his lab at the police station. Just as The Flash is telling Wally that a bolt of lightning came through the window and hit the chemicals as they splashed over him, the same thing happens to Wally.

On TV, Wally becomes a speedster on Earth 1 when he is exposed to a wave of Dark Matter, in the Season 3 episode "Killer Frost." Another version of Wally served as The Flash when the timeline was altered during Flashpoint.

13 STAR LABS

STAR Labs on The Flash

On TV, STAR Labs is the home base for Team Flash. It was established by Dr. Harrison Wells to house the particle accelerator, a clean energy source for Central City -- or so we were told. In truth, Wells was being impersonated by Eobard Thawne, the Reverse-Flash, and he sabotaged the accelerator in a scheme to return to the 22nd century, his home time period.

S.T.A.R. Labs -- for Scientific and Technological Advanced Research Laboratories -- was a mainstay of the Superman titles in the 1970s and '80s, first appearing in Superman (Volume 1) #246 (December 1971). S.T.A.R. Labs in the comics is a global organization, headquartered in Metropolis, with sister facilities in Japan, Australia, Canada and many major cities in the United States.

12 A BETTER VIBE

Carlos Valdes as Vibe on The Flash
The Flash -- "Dead or Alive" -- Image FLA311a_0443b.jpg -- Pictured: Carlos Valdes as Cisco Ramon -- Photo: Diyah Pera/The CW -- © 2017 The CW Network, LLC. All rights reserved.

In Justice League of America Annual #2 (1984), team leader Aquaman ordered the big guns -- Superman, Batman, Wonder Woman, etc. -- to resign if they couldn't commit to the team full time. Most of their replacements were new and untried heroes, such as Vibe. He was Paco Ramone, a street gang leader and breakdancer who could generate shockwaves.

For TV, Vibe was renamed Cisco Ramon and given a stronger array of abilities. His powers let him tap into dimensional energy. Among the things he can do is create concussive blasts of energy; "vibe," witnessing past or future events across time, space or different dimensions; "breach," fashioning portals to other dimensions.

11 RESIDENT GENIUS

cisco and harry crisis on earth-x

TV's Cisco Ramon is a whole lot smarter than his four-color forebear. As a mechanical engineer and scientist at S.T.A.R. Labs, Cisco helped build the particle accelerator. Cisco invented the Flash's suit, which is installed with tracking gear and other functions. He also created the suits for Kid Flash and White Canary.

Cisco invented Captain Cold's absolute zero gun, Heat Wave's flamethrower and Golden Glider's Gold Gun. He made the speed accelerating tachyon device that breached the Flash to Supergirl's Earth, and later made a miniature version as small as a poker chip. He is also an expert computer hacker. And when the Flash was trapped in the Speed Force, Cisco freed him by creating a decoy keyed to the Flash's DNA.

10 ONCE MORE INTO THE BREACH

The Flash -- breaches with Cisco, Barry and Harrison Wells

In the comics, Barry Allen used a device he invented called the cosmic treadmill to accurately travel to specific points in time and space. The cosmic treadmill first appeared in The Flash (Volume 1) #125 (December 1961). He can travel through time without it, but the cosmic treadmill lets him land precisely where he wants.e

TV's Flash gets around to other worlds via "breaches," small wormholes between dimensions. Team Flash has opened breaches with technology, and Vibe is able to generate breaches with his powers. Beings who are tied to the Speed Force may also travel using breaches. The interdimensional extrapolator Cisco invented allows The Flash to make breaches letting him travel to Supergirl's Earth and vice versa.

9 RONNIE RAYMOND AND CAITLIN SNOW

Ronnie Raymond (Robbie Amell) and Caitlin Snow (Danielle Panabaker) in Arroverse's The Flash
Ronnie Raymond (Robbie Amell) and Caitlin Snow (Danielle Panabaker) stand side by side on The Flash.

The ill-fated relationship of Ronnie Raymond and Caitlin Snow blends several elements from the comics. There, Ronnie Raymond is half of the being Firestorm, and Killer Frost was a recurring antagonist. But there were three different women who adopted the Killer Frost persona, Crystal Frost, Louise Lincoln and Caitlin.

On TV, Ronnie and Caitlin were on the STAR Labs staff, and he proposed to her ahead of the particle accelerator startup. The faulty launch merged Ronnie with professor Martin Stein, fusing them into Firestorm. Eventually, the two were separated, and Ronnie and Caitlin got married. However, Ronnie was sacrificed while defeating a singularity that hovered over Central City in the Season 2 episode "The Man Who Saved Central City."

8 KILLER FROST, FRENEMY TO TEAM FLASH

Killer Frost in The Flash

The Caitlin Snow version of Killer Frost first appeared in Justice League of America: Killer Frost #7.2 (November 2013), and soon became a Firestorm antagonist. TV's Killer Frost is an alternate personality of Caitlin Snow. She was believed to have developed the Killer Frost powers from the particle accelerator explosion, but it was revealed in Season 5 that her father performed genetic experiments on her.

After powers surfaced, Caitlin has struggled to contain her Killer Frost persona, which is more sarcastic and vicious than she is. Killer Frost formed an alliance with Savitar to destroy The Flash, but changes sides in the end. Caitlin and Killer Frost have became allies with Team Flash.

7 EDDIE THAWNE IS NEW TO TV

iris west, eddie thawne

Detective Joe West's partner in Season 1 was Eddie Thawne, formerly of the Keystone City Police Department. Eddie also began dating Joe's daughter Iris, although they hid the relationship at first. Eddie became a friend of Barry Allen, which was awkward because Barry was beginning to develop romantic feelings for Iris. However, things progressed between Eddie and Iris to the point where he proposed.

Barry revealed he was The Flash to Eddie but swore him to secrecy to protect Iris. This strained on Eddie's relationship with Iris, which grew as he helped Team Flash investigate the Reverse-Flash. Eddie learned he is an ancestor of the Reverse-Flash, and sacrificed himself to prevent the villain's existence. Eddie Thawne is a character unique to The Flash TV series.

6 EOBARD THAWNE POSED AS HARRISON WELLS

719597-cool-eobard-thawne-wallpapers-1920x1080-smartphone

Eobard Thawne, the Reverse-Flash, has been The Flash's arch enemy since The Flash (Volume 1) #139 (September 1963). Thawne is a 25th century crook who finds a time capsule holding one of The's Flash suits. Using future technology, Thawne develops superspeed. The Flash comes to the future to prevent an atomic explosion, and defeats Thawne. A vengeful Thawne targets The Flash, ultimately taking Iris Allen's life.

On TV, Thawne is a speedster from the 22nd century. He became trapped in the past when he tried to eliminate Barry Allen in his boyhood and did in his mother instead. To get back to his own time, Thawne impersonated scientist Harrison Wells and triggered the particle accelerator explosion to create The Flash and improve his speed.

5 A DIFFERENT RALPH DIBNY

The Flash Ralph Dibny

Ralph Dibny, the Elongated Man, first appeared in The Flash (Volume 1) #112 (May 1960). He was an amateur detective and adventurer who developed the ability to stretch his limbs and body from ingesting an extract of the gingo plant. Ralph was a rare comics hero who did not hide his identity and was happily married, to the former Sue Dearborn, who helped him on his cases.

On TV, Ralph is a former Central City Police detective forced to resign after Barry Allen proved he planted evidence. He became a private investigator and developed elastic powers after being exposed to dark matter, and joined Team Flash. Wife Sue has not appeared the TV's The Flash.

4 ONE CHILD, NOT TWO

During the "Crisis on Earth X" crossover, a mysterious girl showed up, and popped up in several Flash episodes after that until the Season 4 finale, where we learned she's Barry's and Iris's daughter, Nora. During Season 5, we learn Nora is a speedster from the future out to connect with her parents.

In the comics, Barry Allen and Iris West retreat to the 30th century after the Crisis on Infinite Earths. They have a twin son and daughter, Dawn and Don Allen. Dawn and Don are speedsters known as the Tornado Twins. TV's Nora is a composite of Dawn and Don and Jenni Ognats, a speedster who in the comics is Dawn's daughter and Barry's and Iris's granddaughter.

3 D.A. CECILE HORTON

The Flash -- Cecille Horton

"The Trial of The Flash" storyline ran during the final two years of The Flash (Volume 1), in issues #323-#350 (July 1983-October 1985). The Flash was charged with manslaughter for breaking the Reverse-Flash's neck while saving the life of his fiancee, Fiona Webb, in issue #324 (August 1983). The Flash's defense attorney was Cecile Horton, who held a grudge against him because he didn't save her father from the villain Goldface.

On TV, Cecile is the Central City District Attorney. She first appeared in Season 1 and frequently interacted with Detective Joe West. They became romantic partners in Season 3 and had a baby daughter in Season 4.

2 IRIS KNOWS BARRY'S SECRET

The Flash Barry Iris

In The Flash series debut, Barry Allen comes out of a nine-month coma with speedster abilities and Team Flash trains him in how to use them. Barry keeps secret his changes from Iris, but she learns he is The Flash after he saves her from an attack by the Reverse-Flash. She is hurt by the deception, but over time they reconcile, fall in love and marry.

In the comics, even though they are engaged from the beginning, Barry doesn't share his secret with Iris. Not even after their wedding, in The Flash (Volume 1) #165 (November 1966). He resolves to tell her on their first anniversary, in The Flash #174 (November 1967), but she says she already knows -- because he talks in his sleep.

1 UNFORGIVABLE

Barry Slows Time for Iris in The Flash season four

As noted above, Barry and Iris have been a couple from the beginning, destined to be together always -- in the present, or centuries into the future. Even when Barry was without Iris and other love interests were introduced, like Fiona Webb, their destiny together is assured.

The Flash TV series also assured us of their love. But it stumbled badly at the outset by having Barry grow up in the West household. The show gave Barry and Iris other love interests, matching Iris with Eddie Thawne, and Barry with Linda Park and Patty Spivot. But it took some heavy lifting to get rid of the creepy vibe of Barry and Iris as de facto brother and sister.