Barry Allen aka the Flash is one of the more sympathetic DC heroes and also currently the most popular superhero who wore the name of the Flash even though there have been multiple men with the same superhero name and powers.
That's partially caused by the successful Arrowverse TV show with Grant Gustin playing Barry and also because of the DCEU where Ezra Miller portrayed the same part as Gustin did. Barry Allen is a pretty good guy, clever and funny, who cares about his friends, but nobody's perfect and even Barry has done some really bad things over the years.
10 He Took Superman's Side In Injustice
Barry usually has a pretty strong moral codex and makes the right decision when it comes to deciding with whom he should team up, at whose side he should fight, whom he should support.
But that wasn't the case in the Injustice series where he joined Superman's side even though the Man of Steel went insane after Joker tricked him into murdering his wife Lois and he started killing people. Superman decided to control the Earth, killed other heroes and Flash still stood by him, even though he realized his mistake and changed his mind in the end.
9 He Keeps Lying To Iris
Considering how much he says he loves his girlfriend Iris West, Barry sure spends a lot of time lying to Iris. Yes, it's difficult to be a superhero, lead a double life and try to keep your loved ones safe but Barry sometimes takes it too far.
More specifically, in the Rebirth line, he keeps lying to Iris as he tries to hide the truth about his secret identity from her. Iris isn't stupid and she quickly realizes that Barry is hiding something from her which naturally drives a wedge between them. So it's only natural that Iris would be mad at Barry once she learns the truth.
8 He Attacked His Friends
Let's go into the Arrowverse for a moment. Barry is somewhat hot-headed as he discovers his powers and he sometimes thinks he knows the best even though the opposite is the truth. During his show's run, the Flash was mind-controlled more than once and it usually had some gruesome consequences.
At one time, he attacked Iris' boyfriend Eddie and then hurt one of his closest friends, the Green Arrow. Another time, he almost killed the Speed Force itself and also attacked his friends. Everybody makes mistakes but Barry still should be more careful. After all, with great power comes great responsibility (the wrong universe, but it's still true).
7 He Was Responsible For Creating Savitar
Also in the CW's Flash, Barry has faced a lot of enemies. But one of the most dangerous ones was none other than Barry himself.
More specifically, a future version of him that went bitter and violent after everybody he loved died and he decided to go back in time and kill Iris, the person Barry loves most. Savitar's creation was entirely Barry's fault then since Savitar was originally a time remnant Barry had created to defeat Zoom.
6 He Killed His Enemy
The one thing that makes superheroes different from the villains they face is their above-mentioned moral codex which usually manifests in the way that they decide not to kill people. The Flash broke this rule when he decided to go back in time to stop several crimes.
He first stopped at Gorilla Grodd's lair and chose to kill his enemy by planting a mini bomb in Grodd's head. When the bomb exploded, so did Grodd's head and the superintelligent ape died.
5 And Was Responsible For Another Villain Killing Himself
List of Barry's bad deeds, at least where his enemies are concerned, doesn't end with Gorilla Grodd's death. He was also responsible for the villain The Top going insane and then killing himself. During the Identity Crisis, Barry came across The Top who had no mercy for anybody.
Barry asked Zatanna to wipe The Top's mind, changing him into a better person and replacing his personality. But it didn't quite work since even though The Top did change into a better person, he recalled his former actions and was so horrified by them he committed suicide.
4 He Also Had Another Villain Mind-Wiped
The Top isn't the only villain who was the victim of Barry's decision to mind wipe those who seemingly couldn't be stopped in a different way. Another villain who met this fate was Doctor Light. To be fair to Barry, the whole League voted whether to wipe Doctor Light's mind after he assaulted Sue Dibny.
But it's Barry who has the power to decide which option it will be since half of the League is against the mind-wipe and half supports it. Barry votes yes and lets his colleagues turn Doctor Light into a shadow of his former self. What's worse, when Batman finds out what they're doing and tries to stop them, Barry also lets his fellow superhero be mind-wiped.
3 He Killed Wally
Wally West and Barry didn't always get along but they usually didn't try to kill each other. That changed in the already mentioned storyline in which Barry went back in time.
First, he killed Grodd, and then he decided to kill his older self... because he wanted to stop past Barry from making serious mistakes, at least that was the explanation. Unfortunately, a future version of Wally appeared on the scene and the future Barry killed him with a hit previously aimed at the past Barry.
2 He Killed The Reverse-Flash
Barry had his fair share of run-ins with truly dangerous villains but none other has so negatively affected his life as his arch-nemesis the Reverse-Flash. The Reverse-Flash killed Iris. And when Barry found someone new to love, Fiona Webb and the two got engaged, the Reverse-Flash also went after Fiona.
That enraged Barry so much he once again broke his code and murdered the Reverse-Flash. He was then accused of the murder, sentenced and found guilty but instead of facing the judgment, he ran to a different time to escape the consequences of his actions.
1 He Created Flashpoint
No matter how many people he may have killed or had mind-wiped, the worst thing Barry Allen has ever done was creating the Flashpoint and changing the lives of so many people - for the worse. Barry went back in time and stopped his mom from being murdered.
Unfortunately, he changed the reality and the world transformed into a horrific place in which the Amazons fought the Atlanteans, Bruce Wayne died as a kid, Superman was imprisoned by the government, and the list goes on. Losing his mother was terrible for Barry but it was still selfish of him to do what he did. Luckily, he fixed it in the end.
