For a Long Runner show, it's to be expected that The Flash (2014) would garner quite a lot of characters with polarizing reception.
Multiple Seasons
- Barry Allen himself, quite possibly being the most controversial of the show leads. People are split between those who feel he's a likeable character whose mistakes are reasonable, and those who feel he's a selfish idiot that really can't be trusted with the power he has.
- Iris West. In Season 1, she was either considered heartwarming for the way she cares for Barry or annoying with her Locked Out of the Loop subplot. Season 2 she was more liked outside of shipping wars, but over season three the "Save Iris" arc made people split on if she was an annoyingly useless Damsel Scrappy or a compelling character that was being poorly used and handled her apparently upcoming death with grace. In the fourth season, the fact that she became a leader in Team Flash was divisive, with some people thinking her role is unjustified thanks to her lack of both a scientific background and general experience, while others praise her new role as making great use of her journalistic instinct and the fact that as the least-suited for field work, manning tactics back at base made sense, not to mention she has far more emotional stability than other Team Flash members. She also got attacked for her initial tension with Barry when he returned while others actually agreed with her complaints regarding Barry's post-return attitude. While some warmed up to her after Seasons 5 and 6 sought to give more focus to her journalism, others still considers her poorly written.
- Wally West is rather divisive. His initial angst, rudeness and extreme Chronic Hero Syndrome made him come off as unsympathetic to some, which was not helped by his controversial Race Lift to a black lad and his modification from Iris's nephew to her brother. Once he gains powers and the team stop trying to push him away from heroics, though, fandom seems to have split between if he's a good part of the show for being Fun Personified in his role as Kid Flash and bringing levity to an otherwise dark story, or if he's distracting and unneeded, especially given his increased prominence as Barry's protege and the potential for him to take over the show completely. Season 4's poor treatment of him however made many fans cry foul, to the point Legends of Tomorrow had to step in and transplant him over to their show.
- Caitlin Snow has become this over the years. Many fans love the character, claiming she is charming and that her alter ego Killer Frost delivers some of the best scenes in the series. Other fans find the character generic and feel that the writers have no idea what to do with her, stating that Killer Frost's plot is a mess due to Frost's inconsistent writing around her abilities and role.
- As seasons passed, Cisco Ramon has become more polarizing with time. Some still find him funny and relatable, while others think that the writers no longer seem to know what to do with him, that he has lost the charm he had in earlier seasons and that he should be Put on a Bus at this point. Having said that, when he finally does depart the show, most fans were sad he was gone and wanted to see him again.
- Jesse was highly anticipated by Flash fans and her own fans since she's long been in limbo in the comics, due to the edict that Barry not have a Flash family. The show's version of her however; either she's another poor attempt to make yet another adorkable girl character in a franchise that already has too many, and her workaholic personality was removed for no reason to make her yet another Damsel in Distress who needs to be rescued, or she's a good character who grounds Harry and gives the viewer not only a more normal character in general, but also a more normal Earth-2 character, in terms of how she reacts to everything. Even supporters want her to eventually move more in-line with her comic counterpart, however.
- Ralph Dibny. Some love him for being funny, Hartley Sawyer's performance, being less angsty than Wally (at first) and being a protege to Barry who isn't another speedster, but others see him as a Replacement Scrappy for Wally, an out of place character in general, an annoying misogynist, and pointless comic relief with juvenile and crude humour that ruins the tone of the season, all of which isn't helped by how Ralph is portrayed as an Adaptational Jerkass. He outgrows the misogynistic aspects of his character, but his constant cycle of not wanting to be a hero only to be persuaded later, and then forget that lesson in the next episode has grated on many fans. While his hatred has subsided since he became a Nice Guy in Season 5, he is still one of the reasons why Season 4 was poorly received.
- Nora West-Allen. While she was warmly embraced in her few appearances in Season 4, she became polarizing starting from Season 5. One half of the fanbase loves her and the unique dynamic she brings to the team, while the other finds her to be too childish to be likeable and considers her presence as a regular to be ridiculous, accusing Team Flash of Protagonist-Centered Morality for letting her be in the present and change the timeline to her benefit. Her relationship with her parents and especially with Eobard Thawne has been hotly debated too. Some fans thought her initial animosity towards Iris as well-deserved due to them considering future Iris's actions to be unforgivable or plainly disliking Iris, while others thought she was being too rude to a mother trying to connect with her and that hadn't dampened her powers yet. Her affiliation with Thawne was seen as either understandable due to her naivete or as unacceptable given that she shouldn't have trusted a major Flash enemy and she hid said affiliations from their parents and the rest of the team for a long part of the season. The problem became worse as the season wore on, and she began to show arguably manipulative tendencies, like forcing Cisco to build a machine for her by pressing a Trauma Button.
- Eobard Thawne himself, especially the Tom Cavanagh version, mostly because he just won't go away. While he started off as a beloved Breakout Villain, over the years his returns got more and more polarizing. Some argue this is as it should be since he's Flash's oldest and most dangerous foe; others are simply tired of him popping up again and again no matter how definitely he was killed the last time around. Despite this, people don't exactly hate Thawne as a character, it's just that some think he's overstayed his welcome to the point of absurdity and it's time to retire the character.
- Amunet Black. Is her portrayal a delightful Ham and Cheese performance that neatly contrasts with the quieter and far more menacing DeVoe, or is she a cheesy under-performing villain who weakens episodes she appears in and her fake British accent so distracting that it makes the character outright annoying?
Season 2
- Zoom, depending on who you ask, is either an one note Invincible Villain with an anti-climactic Evil Plan and a poor substitute for the more engaging Reverse-Flash, or a terrifyingly intimidating and incredibly badass villain and worthy successor to Thawne. When his true identity is revealed, fans remain split on whether he's an awesome villain with a tragic backstory or a cheap Replacement Scrappy with a completely inconsistent plan and personality who ruins the comics' version of Hunter Zolomon with his Adaptational Villainy. And then there's a third group of fans who believe that he's a good villain in his own right but a poor adaptation of the source material.
- Julian Albert, the new CSI tech. Some loved him for Tom Felton's awesome acting and his frequent Jerkass Has a Point status. Others dislike him since he's an Insufferable Genius who nearly got everyone in the police station killed in Episode 3 because he decided to confront a metahuman all by himself just to prove his theory right rather than follow basic police protocol and he later blackmailed Barry while complaining about Barry's morality. It also really doesn't help when we learn that he's Doctor Alchemy, one of the major villains this season, though "The Present" shows he was something of a physical avatar/mouthpiece for Savitar and completely unaware of his alter-ego while giving Julian another chance to mend the fence with Barry. Even after that, his relationship with Caitlin was seen by many as Strangled by the Red String and Romantic Plot Tumor, and his treatment of her being Unintentionally Unsympathetic.
- Savitar is likely one of the most divisive villains in the entire series. Some are irritated that yet another speedster serves as the Big Bad and consider him a bland repeat of Reverse-Flash and Zoom, while others don't mind and feel that speed-based villains are the best to combat Barry. This just worsened when it was revealed that Savitar is a future time remnant of Barry Allen who turned evil. The fandom is torn between those who thought it was a clever twist, those who were happy to have predicted Savitar's identity correctly, and those who are disappointed that the show went with the most obvious and predictable fan theory which wasn't shocking at all. There's also further divisive opinions on whether the reveal of Savitar's true identity was an improvement to his character or made him worse. A portion of the fanbase who felt Savitar was generic and lackluster before became interested after the reveal due to curiosity over how a future Barry Allen became Savitar. Another portion felt that making him a future Barry took away his intimidation factor of being the "God of Speed" as he's really just a vulnerable man underneath, though others argue that Savitar was never intimidating to begin with and was just silly prior to the reveal.
Season 4
- Big Bad DeVoe himself falls into this category. For instance, IGN's reviews seem to enjoy the gravitas and menace the character lends to the season along with the ensuing Story Arc it entails, while AV Club's reviews conversely feel that the show's writers themselves aren't smart enough to write for what is supposed to be the world's smartest man, making the end result seem underwhelming, and appreciating when the show takes a break from the serialized conflict. He becomes all the more polarising when Neil Sandilands stops portraying him in favor of the Bus Meta actors, whose bodies DeVoe keeps stealing. For some, the continued body theft misses the point of the intended Brains Evil, Brawn Good conflict, even if later episodes establish that DeVoe's new hosts suffer from Possession Burnout due to inheriting his ALS, thus necessitating his constant bodyhopping.
Season 5
- Cicada II AKA Future Grace Gibbons. While she's near-unanimously agreed to be a step-up from her predecessor and uncle, the fanbase is still divided on whether or not she actually makes for a good villain. Her supporters cite her as having an actual plan to eliminate all meta-humans, being creepily ruthless and insane in her goals, and see the Plot Twist of her as the actual Cicada to be a surprisingly good twist. Her detractors cite her as continuing the infamous Arc Fatigue of season 5, still think she's not a competent enough villain to face Team Flash without subjecting them to The Worf Effect, and see the Plot Twist of her being the actual Cicada as lazy and forced due to fans not liking the original Cicada.
Season 6
- Harrison Nash Wells. Aside from the It's the Same, Now It Sucks! regarding new Wells characters, there have been mixed views for Nash. Some like his character, while others have stated that his writing is inconsistent and confusing, specially when it comes to his role as Pariah. His role with Allegra Garcia has also been controversial.
Season 9
- Red Death. While some were tired of yet another speedster villain in a series that's absolutely teeming to the brim with them, others thought she was an interesting twist on the old concept by making her an artificial speedster. Some found her suited-up acting to mirror the intimidation factor of Reverse-Flash and Zoom, while others found she fell flat and wasn't compelling at all and found her lines to coming across as overly edgy. What can be agreed by both sides is her rage-filled breakdowns detracted from her seriousness and made her more annoying. However it should be noted, there's quite a lot of Batwoman fans who appreciated the return of Javicia Leslie as a version of Batwoman and how The Flash attempted to provide closure for the cancelled show, with even the real Ryan Wilder/Batwoman making an appearance.
