For one reason or another, a surprisingly high number of comic book characters have caused controversy over the years. Whether they're just generally controversial, have done controversial things in canon, or have sparked fan controversy through the way they've been depicted or adapted, heated discussions and public disagreements have been caused by them on a number of occasions.
Spider-Man is up there with Batman and Superman as one of the most popular comic book movie characters of all time - as a result, he's had five huge solo movies and has recently appeared in the Marvel Cinematic Universe for the first time in Captain America: Civil War, which will undoubtedly boost his popularity even further. He's also generally considered to be the least controversial of the most popular superheroes, as he is much "lighter" in tone than the likes of Batman - but it's easy to forget a particular story of his that caused massive amounts of controversy. That story was 2006's Reign, in which it was revealed that prolonged exposure to Peter Parker's radioactive sperm had caused Mary Jane Watson to die of cancer. For a Spider-Man story to take such a dark turn was seriously controversial.
Iron Man has gone from being something of a B-list hero to one of the most popular in all of fiction in recent years - thanks largely to his portrayal by Robert Downey, Jr. in the Marvel Cinematic Universe. However, the comic book version of the character has caused a lot of controversy in his time - mostly for his alcoholism. Downey, Jr.'s Tony Stark likes a drink, but the Demon in a Bottle comic book arc from 1979 saw the character descend into full-blown alcoholism after accidentally killing an ambassador. It was a brilliant and engaging storyline - one that defined the character, in fact - but having such an adult storyline in a comic book was extremely controversial at the time. And the fact that alcoholism has since become an ever-present theme in the character's stories only adds to that.
For many, many years, Captain America has been seen as the most righteous, virtuous, courageous and morally sound superhero in fiction. His popularity in comic books has been reflected in the Marvel Cinematic Universe, where Chris Evans has portrayed him since 2011. But recently, in the comic books, his entire history has been controversially turned on its head. In 2016's Captain America: Steve Rogers #1, the final panel revealed that Captain America - real name Steve Rogers - has actually been a HYDRA double-agent since his early youth. For a lot of fans, this was just too much - HYDRA have been his arch-enemies for years and they represent everything he was supposed to hate. It will be extremely interesting to see where Marvel take this arc going forward, but some fans will simply never accept it.
The Joker is one of the most despicable villains in all of fiction. He has transcended the comic book genre - and indeed the concept of being a villain - by starring in multiple live action movies and becoming one of the most popular comic book characters ever. However, almost everything he does could potentially cause controversy. We could be here all day talking about him in that respect - but there's one story in particular in which he was incredibly controversial. The Killing Joke - 1988's brilliant one-shot graphic novel from DC - saw the Joker at his most vile and brutal. The lunatic villain permanently crippled Barbara Gordon by shooting her in the spine, before caging her and forcing her father - Jim Gordon - to look at pictures of his daughter injured and naked. In hindsight, The Killing Joke is seen as THE definitive Joker story, but his crippling and subsequent humiliation of a beloved superheroine did not sit well with fans at all.
As a comic book character, Deadpool causes controversy for numerous reasons - he's a TOTAL rip-off of DC's Deathstroke for starters, his stories deal with cancer in a fairly controversial way, he doesn't give a damn what he says, and he inexplicably breaks the fourth wall, for example - but the character is a HUGE figure of controversy in movies too. First of all, in X-Men Origins: Wolverine, Fox totally butchered the character by sewing his mouth shut and giving him a bunch of new and unnecessary powers. Then, more recently in this year's Deadpool, the fact that his movie was rated "R" for its extremely explicit language, gory violence and scenes of a sexual nature - in a time when comic book movies attract kids in their millions - was extremely controversial. However, it's impossible not to love him anyway.