In the Apokolips War film in 2020, Barry disappeared into the Speed Force to create another Flashpoint and his status is currently unknown. Due to this, Barry was responsible for resetting the timeline for the greater good as a lot of the the Earth's population was gone and most heroes had perished.
In his youth, Barry Allen liked to rush in any activity he did. His mother's car broke down one day and he was frantic to receive help. Barry's mother instead taught him a prayer that her grandmother once taught her; "Accept the things you cannot change, have the courage to change the things you can and have the wisdom to know the difference". Barry didn’t completely understand this and raced his mother to receive help at a gas station.
Returning home one day for his mother's birthday, Barry found that his house was broken into and his mother was killed as a result of this. He soon attended her funeral, traumatized.
Barry soon began working for the CCPD and was caught in a freak accident when he was struck by lightning and splashed with chemicals. He found out that as a result of this, he was connected to the Speed Force and was given super speed. He then uses these powers to fight crime in Central City, against villains such as Captain Cold and Eobard Thawne, A.K.A. "Professor Zoom".
Barry later joined other superheroes to found the Justice League. A museum, named the Flash Museum, was built in his honor as a service to protecting Central City and the world itself.
With his wife, Iris West, they visited Nora Allen's grave on her birthday with Barry blaming himself for his mother's death. He soon got an alert that there was a break-in at the Flash museum. Barry found himself facing against the Top, Mirror Master, Heat Wave, Captain Cold, Captain Boomerang and Professor Eobard Thawne who assembled the villains and put bombs on each of their belts in an attempt to destroy Central City, along with thousands of others. Barry manages to attach the bomb placed on himself onto Zoom in order to try and force Zoom into disabling the bombs. However, Zoom still refused and the Justice League (Batman, Superman, Green Lantern, Captain Atom, Cyborg, Wonder Woman and Aquaman) arrive to help Barry and defeat Zoom. When being taken to S.T.A.R Labs, Zoom leaves Barry with an upsetting statement of how he can't save everyone that matters most to him. Barry then runs off, contemplating what Eobard said.
Barry awakens at his desk and found himself in a new timeline where his mother is still alive but he’s not the Flash and has no powers, Iris is married to another man, Bruce Wayne is dead, the Justice League doesn't exist and a war rages on between the Atlanteans and the Amazons. After seeing Iris married to another man with children, Barry completely devastated travels to Wayne Manor looking for Bruce. When he arrives, he finds Wayne Manor in a completely dilapidated state. He gains access to the Batcave and is assaulted by Batman who in this timeline is Thomas Wayne and Bruce was killed instead by Joe Chill, driving Thomas to become a more brutal Batman. After Thomas allows Barry to open his Flash ring, he finds Professor Zoom's costume in it. Barry automatically blames Professor Zoom for messing with the timeline.
He enlists the help of Thomas Wayne to help regain his speed. Barry tried to recreate how he gained his powers; the first attempt leaves him with third degree burns but the second attempt succeeded.
Barry tried to break the time barrier in order to revert the timeline back to normal but a disruption in the Speed Force prevented him from doing so. Barry enlisted the help of Batman and Cyborg to find the timeline's Superman in hope that he could change the timeline. However, the Superman that they found was weary and less brave than the Superman that Barry once knew. This Superman flew away in fear of his newfound abilities.
Barry found his memories changing and so the trio recruited the Shazam kids to stop the feud between the Atlanteans and the Amazons. Batman showed Barry a picture caught by Lois Lane's camera and Barry recognized it as an image of Zoom. In the heat of the war, Barry got caught in a fight with Professor Zoom which ended with Zoom severely beating him. He then revealed to Barry that it was Barry himself who created Flashpoint, who went back in time and saved his mother, taunting Barry that all of this is his fault. He then made a last ditch effort to fight Zoom. However, Zoom while displaying his connection to the Speed Force told Barry, that as long as he can siphon it, he’s the the one preventing him from altering the timeline a second time.
At the same time, a dying Aquaman pressed the symbol on his belt which sent a signal the machine holding Captain Atom which caused him to detonate and create a nuclear wave which will destroy the world. Thawne paraded his arrogance to Barry telling him that as long as he's alive there wasn’t enough Speed Force energy for Barry to change the timeline. At that moment, Batman shot Eobard in the back of the head killing him. As Batman collapse, he remarks that Flash can use the Speed Force now. Wounded, he removed his mask and told Barry to change the timeline and prevent this world from ever occurring and handed him a letter to deliver to Bruce, then died from his wounds. Barry, exhausted and hurt ran as fast as he could away from the destructive wave and broke the time barrier heading towards his past self. As he pleaded with his past self to stop, he pushed Barry away believing him to be an impostor. Barry with last ounce of strength and energy ran fast as he could and collided with his past self, letting Nora Allen die as she was meant to and restoring the timeline.
After colliding with his past self in the Speed Force, Barry awoke at his desk to find that the timeline had been returned to normal. He later visited his mother's grave, laying flowers and finally accepting her death. Iris arrived at the grave and the two embraced. He later visited Bruce in the Batcave and told him that even though he restored the timeline he still retained his memories of growing up with his mother in the Flashpoint timeline. Bruce suggested that it might have been a gift from the Speed Force, allowing him to keep the memories of two lives. Flash then presented Bruce with Thomas's letter as promised. Batman removed his mask as he believed this was a letter for Bruce himself. Reading the letter reduced the Dark Knight to tears. Bruce then told Barry "You're one hell of a messenger". A happy Barry then left the cave heading to Central City. After stopping his past self from creating the Flashpoint Paradox, Barry arrives in the new timeline at the exact moment he left. This causes the Barry of the Original, Flashpoint and New timelines to all merge into one. As a result Barry now has the memories of his past life, his Flashpoint life and his new timeline life. By this point in history, the Justice League was formed many years ago. Barry and Bruce know each other very well and he knows the location of the Batcave and has a new Flash suit.
Justice League: War
After discovering a Parademon attempting to plant a Mother Box in Central City, he subdued it, and brought both the creature and device to S.T.A.R. Labs for study. A few days later, while coming back from a burrito run for the CCPD forensic department, Barry called Dr. Silas Stone to see whether or not they had found out anymore about the creature and device. When S.T.A.R. Labs was attacked by an army of Parademons, Dr. Stone and his team were in the Red Room attempting to save Silas's son life, Barry called just as the Parademons began to break into the room. He was told by Dr. Stone that they were in trouble, and rushed down to S.T.A.R. Labs as the Flash to assist them. After defeating several Parademons with ease, and being saved by Silas' son Victor, who had been turned into a cyborg after an accident with a Mother Box, he left for downtown. Flash then helped Victor fight off the attacking Parademons. He then left to give the father and son some privacy. Later When Green Lantern and Batman were fighting more Parademons in Metropolis Flash came to their aid. After a friendly greeting with his old friend Green Lantern, Flash was awestruck at meeting Batman who was impressed by his work in Central City. Joined by Superman, Shazam, Wonder Woman and Cyborg the group watched as the Parademons leader Darkseid approached. Despite their efforts to fight him off Darkseid overpowered them and captured Superman. While Batman went to go rescue Superman the rest of the team came up with the plan to blind Darkseid. Wonder Woman using her skills and agility was able to blind the first eye with her sword. As the team fought him they managed to restrain him allowing Flash to blind his second eye with a crowbar. However Darkseid was still not down. Cyborg decided that to truly defeat Darkseid they had to send him back through one of the mother boxes portals. After finally getting the Motherbox to activate the portal opened and together with help from a returning Batman and Superman; Flash and the others managed to push Darkseid back through the portal. Saving the Earth. Afterwards he reported to the rest of the heroes about Superman's capture. Barry later followed Green Lantern's plan, After Darkseid's defeat, Barry suggested to the rest of the group that they leave before the approaching civilians blamed them again, though he was surprised as they celebrated them instead. He later attended a ceremony honoring him and the rest of the heroes at Capitol Hill. Later when the team was being honored the president asked if they had a name only for Shazam to come up with the name Super Seven much to the others chargin.
Justice League: Throne of Atlantis
To be added
Justice League Vs. Teen Titans
Barry is possessed by a wraith sent to Earth by Trigon along with the Superman, Wonder Woman and Cyborg. All four of the infected league members arrive outside Titan's Tower and battle the Titan's to abduct Raven. After the possessed members except for Batman who expelled his one by injecting himself with a nerve toxin powerful enough to subdue Bane have the upper hand, Raven agrees to willingly go with them as long as they leave her friends alone. After Superman was freed from the wraiths possession by Damian and his use of Kryptonite he told the assembled Titan's to get Raven out of the machine Trigon was using to escape his imprisonment. Superman engaged the possessed Flash in battle but was unable to catch him. As Flash ran around him Superman apologized to Barry for what he was about to do and jumped up and landed on Flash's left leg breaking it. This caused the wraith to leave Barry's body and dissipate. Barry then told Superman that it would take an hour for his leg to heal while protesting at him for breaking his leg, to which Superman rebuked that Barry had ten minutes. After Trigon was freed from hell and began making his way towards a populated city, Flash and the rest of the league engaged him battle to by the Titan's and Raven time to seal him back in the crystal he escaped. While Superman and Wonder Woman tried to stop Trigon, Barry began evacuating civilians out of the area. He then witnessed as Trigon was contained and sent back to hell by the spell that Raven cast to stop him. He was present at the Hall of Justice with Superman and Wonder Woman as Batman congratulated the Titan's on stopping Trigon and saving the world. 
The Death of Superman
At the weekly team meeting Barry announced to the team that he and Iris were getting married. He also encouraged Clark to tell Lois that he’s Superman. Barry later engaged the rampaging monster Doomsday in battle. He rescued Green Lantern, after Hawkman got taken out after he was severely beaten by the creature. Flash then fought Doomsday with Hawkman's Nth metal mace, severely injuring the creature but was ultimately defeated and rescued by Batman before Doomsday could kill him. He later attended Superman's funeral with the rest of the Justice League.
Reign of the Supermen
To be added
Justice League Dark: Apokolips War
Barry was present for Superman's briefing on the attack on Apokolips. Barry expressed his disagreement with Superman's headstrong plan, having went through the experiences of Flashpoint, but gives up upon seeing Superman's resolve to ending Darkseid before he can make the first move. while the Teen Titans remain on Earth as a home-guard Barry accompanies the Justice League on their invasion of Apokolips. Upon arriving, the League is immediately attacked by the Paradooms, genetic hybrids of Parademons and Doomsday. Despite the League's valiant efforts, they’re utterly decimated by the Paradooms, and most of them are violently killed. Barry is one of the only members whose life was spared as Darkseid had plans for him.
Two years later, after the remaining forces invade Apokolips by using the boom tube from LexCorp with intentions of destroying it, they come across Barry, who’s forced to endlessly run on a treadmill meant as a power generator for the planet. Superman, despite being depowered, destroys the generator and Barry is freed, and John Constantine scans his mind, learning about the Flashpoint which caused the current events. Barry is left in a weakened state as his muscles have withered due to constantly running and his powers are fluctuating as result. The other League members, who were transformed into Darkseid's Furies but were saved, helped him reunite with the other heroes.
After the League's victory over Darkseid, Barry's speed healing has restored his muscles to their peak and his powers fully restored. He’s among the other League members as Batman announces that the Reapers have dealt too much damage to the planet and it was doomed. Constantine informs Barry that he must create a second Flashpoint, who initially refuses to due to his promise to Iris. However, Constantine reasons with him that any changes created by Flashpoint would be better than their current situation, and Barry agrees. Barry runs to reset the timeline as the other League members watch in optimism.
Powers and Abilities
Speed Force Connection/Superhuman Speed: This is his main power. Due to his connection with the Speed Force, Barry has the power to move and think at superhuman speed, making him the fastest man alive. He’s shown to be faster than the normal speed of time, allowing him to defy forces such as gravity to an extent, while he’s also adapted to extreme temperatures, impact, and deprivation of oxygen.
- Superhuman Reflexes: Due to his superhuman speed, Barry can react faster as such.
- Superhuman Agility: Barry's agility, balance, and bodily coordination are enhanced to superhuman levels.
- Superhuman Resilience: Barry has nearly limitless stamina and endurance and can survive being punched by Darkseid through the air and into an exploding car, as well as several other injuries or trauma that would be fatal or crippling to normal humans.
- Superhuman Metabolism: Due to his speed enhanced physiology, he’s resistant to weight gain & heals at an accelerated rate, allowing injuries to vanish within an hour. This metabolism also extends his health & longevity.
- Intangibility: By vibrating his body at super-high speeds, Flash can phase through solid objects by slipping through the gaps between molecules. His intangibility causes pain to living creatures and could be fatal if he stops vibrating for even a second while phasing through a person.
- Enhanced Momentum: Barry is able to control and generate more force than humanly possible, allowing him to simulate having superhuman strength while moving at super speed. This allowed him to stun Darkseid and Superman with his attacks and effortlessly incapacitate both Parademons and Atlanteans, the former of which he left dents on when he punched them. 
- Aerokinesis: By rotating his arms at super-speed, Barry can create strong and intense vortexes of wind.
- Electrokinesis: While moving at superhuman speeds, Barry's body generates Speed Force lightning.
- Accelerated Healing: Any injury he receives also recover from nearly any injury in hours or less, to the point where he can fully heal from third degree burns or broken bones. He can heal from injuries than humans aren’t unable to completely heal from, all without any lingering effects. It’s possible that he may have a highly retarded aging process.
- Time Travel: Barry's speed can breach the temporal barriers, letting him enter different points in time. The first time he time traveled, he saved his mom and created Flashpoint Paradox. When he restored the timeline, he gained the memories of the pre-flashpoint, Flashpoint, and Post-flashpoint timeline.
- Forensics Expertise: Barry is highly skilled in forensic science.
- Despite being a hero and a protagonist, Barry Allen technically has the highest kill count in the entire franchise. This is due to being responsible for the erasure of three realities. Although this is complicated by the fact that most inhabitants will be restored in the next universe/timeline.
- James Tucker posted on Twitter that the Kid Flash in the flashback of The Judas Contract is actually meant to be a young Barry Allen instead of his nephew Wally. However this was never confirmed to be true in universe.
- Justice League: The Flashpoint Paradox
- Justice League: War
- Justice League: Throne of Atlantis
- Justice League vs. Teen Titans
- Justice League Dark
- The Death of Superman
- Reign of the Supermen
- Justice League Dark: Apokolips War
- Corson, Heath (writer) & Oliva, Jay (director) (February 4, 2014). Justice League: War.
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- Justice League vs. Teen Titans