It takes a lot of things to be a hero, but one thing that isn't necessary is a winning personality. As the Marvel universe shows, as long as you battle the occasional supervillain, you can be a rampant asshole to pretty much anyone! Here are eight characters better at being assholes than superheroes.
1) Hank Pym
As Ant-Man, Giant-Man and other monikers, Dr. Hank Pym has saved the world countless times. He's been an Avenger, a mentor, a friend; he's made countless scientific breakthroughs; he's had so many accomplishments. And yet, whenever he's mentioned, the first thing everybody thinks about is the time he punched wife Janet (the Wasp) in the face. Sure, exposure to unknown gases turned him schizophrenic, which triggered his change into Yellowjacket, at which point he kidnapped Janet, told her he killed Hank Pym, and forced her to marry him. But he had been cured of that long before he started verbally abusing his wife. After he was court-martialed for attacking an enemy from behind who was already potentially surrendering; the Avengers court-martialed him, at which point Hank decided to create a killer robot, have it invade Avengers Mansion, and use its secret weak point to defeat it and look like a hero. When the Wasp discovered this plan and pointed out it was, you know, batshit crazy, that's when Pym hit his wife. He eventually got better, but you know the old saying: "Beat one wife, you're an asshole forever."
2) Quicksilver
Quicksilver didn't inherit his father Magneto's powers, but he did inherit his silver hair and his obnoxious attitude. Pietro Maximoff has vacillated between being a bad guy and a good guy for years, but he's always had an attitude — chaffing at Magneto's commands in the Brotherhood of Evil Mutants, rebelling at Captain America's orders as an Avenger, generally being bitter at having to protect humanity when they hated mutants, etc. But his biggest dick move was somehow convincing his emotionally unstable sister, the Scarlet Witch, to rewrite all of reality in the "House of M" saga, which not only tormented people with lives they could never have, but which cost most of the mutant population their powers, including his own. To Quicksilver's credit, he tried to repower these mutants by stealing the Inhumans' Terrigen Mists, which gives people powers, and using it on depowered mutants. Quicksilver quickly learns that these Mists do give people powers back, but also drives them crazy and/or kills them. However, Quicksilver is infinitely more worried about assuaging his guilt over reality, and continues to "repower" people anyways. Including his daughter. Asshole.
3) Namor
Oh, Namor. There may be no one in the Marvel universe quite so arrogant, and this is a world containing Doctor Doom. As the half-human, half-merman King of Atlantis, he's waged countless wars against the surface world. He's joined almost every single superhero group in the Marvel universe, and left them all because he felt he knew better than anybody and thus anytime anyone disagreed with him they were being idiots unworthy of his time (he also left the Avengers because he didn't like taking orders from the Wasp). He has, publicly and repeatedly, macked on Mr. Fantastic's wife Sue for years, sometimes right in front of him. There's a reason the Atlanteans try to overthrow him every two months, and it's not because of his charm. Frankly, I think he's still coasting on the good will he built up fighting the Nazis in World War II.
4) Cyclops
To be fair, Cyclops has troubles. His eyes shoot killer energy beams constantly; the love of his life Jean Grey has died about a dozen times, and she's the most stable relationship he's ever had; and he's tried to lead a group of mutants to protect a world that hates and fears him. And yet Cyclops manages to be a jerk anyways. Whether he's being a humorless dick or an insufferable asshole, Cyclops manages to suck the happiness out of every room, and he makes no effort to be likable. And speaking of his relationships, he did abandon his wife Madeline Pryor and his child one of the times Jean Grey came back from the dead, and then didn't even tell Jean he was married. But he also cheated on Jean with Emma Frost, so he's a jerk in his lovelife as well. It's almost a relief that Marvel allowed Cyclops to follow his bliss and basically turn into the next Magento in the "Avengers Vs. X-Men" storyline.
5) Mr. Fantastic
There's a nerdy cliché that the smarter you are, the less able you are to function socially — like you're so lost in deep thought that being polite, replying to people, or even thinking about someone other than yourself just doesn't happen. This cliché exists because of people like Reed Richards. Now, this makes him rude; what makes him a jerk is his overwhelming ego, his dismissal of everyone's opinions other than his own, and being a condescending prick to his wife for years. YEARS. Basically, poor Sue Richards was Reed's maid/secretary/prostitute for the first decade of the Fantastic Four comic, and Reed treated her as such. Eventually their relationship deepened as his rampant misogyny declined, but he still never bothered to consult with his wife on anything, even regarding their child Franklin. This led to situations where, faced with his son Franklin's massive powers, instead of parenting or discussing the issue with his spouse, he shot his kid in the head with a coma laser while Sue was holding him. He has never told his wife he's a member of the Illuminati, one of five super-powered men who decide the fate of the planet, no has he ever asked her opinion on… anything, really. Moreover, half of the problems the Fantastic Four have ever had is because Reed was experimenting on something he shouldn't have been experimenting on — hell, the Fantastic Four only exists because he forced his girlfriend, her brother and his best friend go into space before he bothered to check if there might be potential consequences. Clearly, Reed believes consequences are for dumb people.
6) Iron Man
Tony Stark is an asshole. A charming asshole, but an asshole nonetheless. We all know he was an unrepentant weapons manufacturer and dealer for years until one of his own weapons was used against him. He's another founding member of the jerk squad known as the Illuminati, and he formed it with the intention of creating a worldwide superhero government with himself as its head, which is impressively egocentric. I could list every time he's slept with a woman and never called her, the times he belittled his friends, or his rash actions both sober and drunk. But really, all you need to know is that Tony Stark supported and enforced the Superhero Registration Act, which caused a superhero Civil War. During this time, Iron Man 1) killed superheroes, 2) cloned supposed friends like Thor without their knowledge or permission, 3) built a prison in the Negative Zone for superheroes, and 4) convinced Peter Parker to reveal he was Spider-Man to the world, putting him and his family in grave danger, getting Aunt May shot by a sniper, and eventually forcing Spider-Man to trade his marriage to the devil for his aunt's life. Now mind you, the Superhero Registration Act was so obviously heinous that only Reed Richards in the Illuminati thought it was a good idea. Even Captain America leading the fight against the law didn't make him see reason! If you're fighting against Captain America, you're fighting on the wrong side.
7) Magneto
Over the past decade or two, the X-Men's most famous foe has turned into something of a hero. He's tried to form his own nation where mutants can live in peace, he occasionally joined the X-Men, and he's generally just stopped being evil. It can be tough to remember when Magneto first arrived in the Marvel universe he was a sneering, egomaniacal villain who was one mustache twil away from being Dirk Dastardly. He wasn't about protecting mutants as he was about killing humans, mutants being the superior race and all (an irony, given his time spent in a Nazi concentration camp, that was eternally lost on him). Granted, he'd seen how humans hate and fear mutants, but it never dawned on him that by constantly attacking humanity that he was only making things worse. (Also, he should probably have not named his revolutionary group "The Brotherhood of Evil Mutants.") Despite his vocal love of mutant-kind, he was a complete asshole to everyone in his employ, belittling them constantly, abandoning them whenever he was mildly put out. He was so constantly shitty that Toad pushed him out of a helicopter into the ocean, for god's sake. Toad.
8) Professor X
But when it comes to Marvel's biggest jerks, no one will ever come close to Professor X. He's been a grade-A asshole since day one. Day -270, actually, seeing as while he was in his mother's womb he decided his twin was evil and thus murdered his fellow fetus. Being born did not change Charles Xavier's assholery. He has never had a problem mind-controlling or mind-wiping friends and family; this included deleting the existence of an entire group of X-Men who got killed on his watch. He mind-wiped Magneto at one point, accidentally importing his mind into his own head, becoming the nigh invincible supervillain Onslaught, who killed so many heroes. He discovered his Danger Room had gained sentience, and not only didn't free it, never bothered to tell anybody, creating another supervillain in the process. Professor X is a constant manipulator and liar; while the others on this list will be a jerk to your face, Professor X will be a jerk behind your back.