Bucky Barnes — just compare his depictions before Brubaker's run on Cap to Brubaker's depiction of the character. Just how many levels of badass did Bucky take? He became Captain America.
For a long time, the Purple Man was just another gaudily-dressed C-List Fodder villain who would turn up every 5 years or so to get his ass handed to him by Daredevil. Then the writers realized what a guy with his level of Mind Control powers could really do. Cue a year-long storyline, in which the Purple Man secretly took over a Fortune 500 company (whose chairman was the father of Daredevil's girlfriend), used its resources to wage a campaign against Daredevil, framed the chairman for his crimes (eventually driving him to suicide), broke up Daredevil's relationship, and mind controlled four of Daredevil's toughest enemies into trying to kill him all at once. A toned-down preview of what The Kingpin would later do in Born Again. The Purple Man was never a joke in any Marvel book again.
He was also a dangerous opponent to Nate Grey in X-Man, casually controlling the resources of Flagsmasher's ULTIMATUM and manipulating circumstances to force the development of Nate's potential as a Reality Warper, who he hoped to have on his leash, all from behind the scenes... then he made the mistake of revealing himself and trying to take direct control of Nate. This did not go as planned, for the simple reason that, as Nate ominously put it, "My body's only vulnerable until my mind decides otherwise." Cue No-Holds-Barred Beatdown. However, the side-effects of this included effectively destroying the life Nate had made for himself up to that point, which isn't insignificant.
Before that, he was an Adaptational Badass in X-Men: The Animated Series, as a Villain with Good Publicity (and good makeup to hide his purple skin) who was mind-controlling the X-Terminators as his personal army. Using his real name instead of ever calling himself "The Purple Man" helped a lot, too, when it came to being taken seriously. (When your real last name is Killgrave, you don't need a villain handle!)
However, all of the badass goes away when he's up against someone who can no-sell his mind control powers and he doesn't have an army of mooks backing him up. Doctor Doom, Captain America, Daredevil, the Punisher, and Thor can all resist him through willpower alone. Deadpool's healing factor contributes to his scatter-brained personality, so Killgrave power's literally cannot get a "grip" on Deadpool's brain. Spider-Man's spider-sense starts setting off alarms so much that Killgrave simply can't get through the interference.
Thor sees Thor gain the Power Cosmic and while it destroyed the Destroyer Arm he's been sporting since War of the Realms, it also regenerated the lost arm it replaced as well as the eye he lost during War.
Sue Storm/Invisible Woman from Fantastic Four is the poster girl of this trope. (Literally— See the top level page.). Originally the Invisible Girl, she was very meek, and her power was only personal invisibility. She was so useless (not many opportunities◊ for stealth◊ came along), the best her writers could say in response to constant fan outcry against The Load (even in-universe◊) was, "Sue pulls her own weight, even if you refuse to acknowledge her contributions only because she doesn't fight aggressively enough for you". It got so bad that a comic had them address the complaints in-universe. Her force field power was added (less than two years after her introduction), and she gradually became better and more versatile with it, especially under John Byrne. More dramatic was the shift from her original meek personality to her current confident one, which her new choice of codename signifies. These days, Doctor Doom himself considers her the strongest of the Fantastic Four. When she believes that the Super Skrull has abducted her child, The Thing has to remind her that it's the Fantastic Four and not the Fantastic One because she's already beating the tar out of the Super Skrull.
The main point where this became truly noticeable was, you guessed it, her name change. The reason for this was the culmination of quite a few arcs: after another time-traveling stint, her, Reed and their kid, Franklin, damn nearly ended up in the hands of Mephisto, and the arc immediately after had a Dr. Doom fallback destroy their entire home apartment building. The proceeding arc was the biggest reason: where the Psycho-Man kidnapped Sue and turned her into Malice, a Brainwashed and Crazy evil version of her using her force field powers with incredible strength, including substitutes of gravity crushing attacks and the ability to cut off a person's air supply with those powers. It took the rest of the FF with some assistance from Daredevil to snap her out of that, and when they went to capture the Psycho-Man, he ended up capturing them and subjecting Sue to incredibly traumatizing Mind Rape, where she believed that her incompetence caused the death of her family, which she retaliated by killing the Psycho-Man with his own mind-raping devices. At the very end of that arc, she replaced the "Girl" part with "Woman" to reflect on the fact that all those events killed the innocence in her.
Patsy Walker started off as an ordinary teenage girl with fairly normal teenage problems. Then she found a left-over suit and we were off to the races — nowadays, Patsy's more well-known for her superheroine career and stint as a member of The Defenders.
Magik. Originally a normal six-year-old girl, she was abducted and sent to the Underworld, eventually ruling Limbo (a duplicate of Hell) as a teenager. She's now far more powerful and more manipulative, with far fewer morals. Had Magik not been temporarily killed off in the 90's, she would likely be even more dangerous.
For that matter, the members of the Intelligencia all took one. The members? Red Ghost, M.O.D.O.K., Leader, Mad Thinker, and Wizard. The fact that these guys (who apart from the Leader, have become jokes in recent times) have become credible threats and being able of capturing Doom, Black Panther, Hank Pym, Beast and Reed Richards is nothing short of impressive.
Iron Man. Extremis. Which would be good enough on its own, but then he got the Bleeding Edge armor. Taken to a whole another level, by upgrading his armor with Asgardian magic at one point.
Iron Man's armor power doubles every 18 months. Look at Armor Wars. One chapter before last, the big bad easily beats him. Last chapter, he builds a new armor and easily beats the villain. Or look at the modular armor's debut (destroys a robot which previously defeated a dozen armors). But Iron Man stays at the same power level compared to Hulk or Thor.
If one character from the Marvel Universe is more entitled to being the poster boy/girl for this trope than Susan, It's Richard "Nova: the Human Rocket" Rider. Nova spent most of his time being one of Marvel's poster boys for brash, reckless and inexperienced rookies trying to show off in front of the big leaguers and tending to get in the way. Then came Annihilation. And with it, enough raw power to drive him insane without special training and mental shielding with help from the Nova Corps' Worldmind. And the Annihilation War itself had given Rider experience, a much more serious attitude after witnessing the horrors of the Annihilation wave, and a whole lot of respect after he managed to end the entire Annihilation War by ripping Annihilus inside-out in retaliation for what he did to the rest of the Nova Corps. Oh, and immediately prior to that, he managed to survive a massive omni-directional blast from an enraged Galactus at near point-blank range. A blast which was so powerful, it encompassed and destroyed more than three solar systems. Since then, Steven Rogers has made him a member of the Secret Avengers, and Nova become the de-facto commander-in-chief for any organized resistance against major interstellar conflicts, with even the biggest and baddest that space has to offer deferring to him. Needless to say, barring his Marvel Adventures counterpart (which put him in the Avengers), Richard was never portrayed as a childish attention-grabbing wannabe ever again.
Marvel Comics villain The Orb. Originally a petty thief with a gigantic eyeball for a head and a Z-list joke even by that era's standards. Come Original Sin, he ends up fusing with one of the Watcher's stolen eyes and with it, gains immeasurable power and knowledge. He shifts his agenda from petty theft to being a silent catalyst for chaos and anarchy, using his knowledge and powers to subliminally "nudge" people into performing their darker desires. He also becomes strong enough to take on both Dr. Strange (albeit a severely depowered Strange) and Baron Mordo (at full power) at the same time.
Spider-Man's writing team is making all his classic villains either take a level in badass or be replaced by stronger and more dangerous counterparts (Vulture, Rhino). Doctor Octopus took control over all of New York's technology with his last appearance, Chameleon (written by, already mentioned above, Fred Van Lente) returned to his original ways, becoming a perfect — and dangerous — impersonator and assassin. Electro can now turn into lightning and destroyed the Daily Bugle building, Sandman can make multiple copies of himself (some of them are murderous), Mysterio took control over the Mafia Maggia with his tricks. Not so classic White Rabbit has been turned from a complete joke into a dangerous drug dealer and crazy killer and together with the Spot and a bunch of C-List Fodder villains — Scorcher, Speed Demon, Bloodshed, Squid, Lightmaster, and Answer — almost destroyed Mr. Negative's criminal empire and defeated his immortal servants and Hammerhead (they lost only because Negative brainwashed Spider-Man and sent him to fight them).
Spider-Man is all about taking a level in badass. That's essentially what happened to Peter Parker from the very start!
And in Spider-Island, after losing his spider-sense and having to learn how to fight without it (Spider-Fu), it has returned and now Spider-Man is even more dangerous! Baddies beware.
He's done this multiple times over the course of his career as he has grown from a raw teen hero into a mature adult one. He's added tools, refined his webshooters, even gotten training from Captain America (who had pointed out to him that relying on instinct in a fight isn't always a good idea).
Mary Jane Watson started off as just a flirtatious, free-spirited love interest for Spider-Man. As time went on, she became his main love interest, and was strong enough that she once beat one of his enemies up with a baseball bat and hardly ever gets captured; she seems well able to defend herself from villains and even rescued Spider-Man when she needed to.
Also, Spidey's one-time girlfriend Betty Brant. After the murder of her husband Ned Leeds, she went from one nervous breakdown to another, was brainwashed by a cult for a while, and in general, was a Damsel in Distress. Eventually, after a long absence from the comic, she came back packing heat and knowing martial arts, intent on finding answers to the reasons behind Ned's death. Even Spidey was shocked at the change she had underwent. During Peter David's run on Friendly Neighbourhood Spider-Man (shortly before One More Day), the highlight has to be Betty saving Flash and Spidey from Arrow using a shotgun with silver bullets (she's a Daily Bugle reporter).
Joke character Hammerhead got this treatment, as part of becoming The Dragon for Big Bad Mr. Negative. He got a reinforced skeleton (made out of canonical Nightmare Fuelnote that is, it actually gives Spidey nightmares... despite the fact that he never actually saw it) and strength and durability upgrades including a Kevlar throat. The very first thing he does is utterly stomp Spidey. As Peter is lying on the floor with a dislocated jaw, he says "Why aren't you a joke anymore?"
Anthony Davis was a second-rate C-List Fodder supervillain known as the Ringer, who was humiliated by Spider-Man before being unceremoniously murdered along with 17 other supervillains by the villain-killing Scourge. A later retcon would reveal that Davis was Not Quite Dead when he was found by a group of agents from the technological terrorist group A.I.M., who were investigating the site of the massacre to steal the technology of the dead villains. He got better when A.I.M. turned him into a cyborg with advanced laser weapons and teleportation powers. Now calling himself Strikeback, Davis proved to be a much better fighter than he ever was as the Ringer, defeating the Vulture, Stegron, Boomerang, and Swarm one after another when he reappeared.
Spider-Man writer Fred Van Lente has been doing this in general with a few F-list villains, taking them and making them into genuinely capable threats. The best example is the Spot, who is developed by Van Lente into a mute killer who's been driven insane by his being trapped in an alternate dimension and who can now only communicate by writing in his own incomprehensible language of dots. We also see just how legitimately terrifying the powers of even the lowliest super-villains can be. More recently, Van Lente has been writing background stories featuring some of the classic Lee/Ditko/Romita villains in the new Web of Spider-Man series that began in late 2009.
The Spot always had what should have been extremely dangerous abilities. He was just too stupid to use them effectively.
In their first encounter, the Spot beats Spider-Man badly. In their next encounter, Spidey knows what to expect and has the endurance to take his "only" normal human level hits until the Spot has used his powers too much and has given an open spot for him to attack. Thus he is only defeated by his overconfidence.
This predated Fred Van Lente's work. The first definitive example of the modern age of Spider-Man comics was Scorpion, formerly an incredibly dim C-List villain at best, becoming the new Venom and thus gaining not only knowledge and experience of how best to fight Spider-Man, but also getting a considerable physical boost despite already being physically (if not mentally) capable of going toe-to-toe with Spidey.
After a pretty successful stint as Venom (see Thunderbolts and Dark Avengers), he is back as the Scorpion in an even MORE powerful scorpion suit. Spidey still bests him, but he certainly has the powers to be a threat these days.
The Mighty Thor: Volstagg the Voluminous, one of the legendary Warriors Three, is an unusual case. Naturally just being a native of Asgard would make you badass by default, but Volstagg originally was the least badass Asgardian around. Despite his constant bragging of his prowess and his past exploits, he somehow managed to either avoid battle or get taken out by a mook in the first round. Essentially he became the Asgardian equivalent of Falstaff, more inclined to attack a leg of mutton than a foe of Asgard. You could often find him after a battle bragging about how great a strategic move his running away from the fight as usualreally was. This lasted until Walt Simonson's run of the book, in which Volstagg was able to prove that, even if he was hugely obese and past his prime, he was still more than capable of dispatching any number of foes, especially if his family were endangered. Subsequent writers have continued this trend, transforming him from a joke character to one of Asgard's staunchest and most capable defenders. In his youth he was known as the Lion of Asgard and recognized as a great warrior, so this may be more a case of regaining some levels of badass. Most recently, after a horribly traumatising experience when he took half-a-dozen Light Elf children, refugees from Malekith's devastation of their realm, into his care. They promptly got burned alive in his arms. Cue a violent Roaring Rampage of Revenge and a major Heroic BSoD. Then, he found the hammer of the Ultimate Thor, one full of the rage and pain of a dead universe. This transformed him into 'the War Thor', who almostdestroyedMuspelheim. Singlehandedly.
Before being captured by Weapon X, Nightcrawler was just a timid teenager that wet his pants. In just some months there he turned into a brutal soldier, killing several agents while trying to escape from the facility.
Storm leads how to control the wind enough to fly. But she still needs to learn how to land.
The Ultimates: The Defenders were introduced as mere delusional superhero wannabes with no powers. Later on they all get powers and become actual supervillains, with the exception of Valkyrie, who joins the Ultimates. Then she kicks the crap out of Venom and nearly cuts him in half with a sword and gives a few A-list villains like Magneto a run for their money.
X-Man: Nate Grey began as pretty badass, with vast Psychic Powers thanks to his being created as a Living Weapon in the Age of Apocalypse reality to destroy Apocalypse. However, those powers weren't entirely reliable, and he was incredibly inexperienced with them. Despite this, he still effortlessly flattened Holocaust, and beat Apocalypse to a pulp, leaving him on a plate for AoA!Magneto. When he hopped over to the mainstream reality, his powers were estimated as being equivalent to those of the Dark Phoenix and he lived in constant, justified, fear of accidentally rewriting reality in his sleep. As time went by, he got stronger and stronger, even though his powers were killing him and switching on and off at random, subconsciously resurrecting both Maddie Pryor and, briefly, Ao A!Gwen Stacy and finally, himself through sheer force of will. Then, he finally got the genetic flaw fixed and becoming powerful enough to treat the Multiverse as his personal step-ladder, step outside of time and take on the Dark Avengers and Dark X-Men minus the Sentry (who had disappeared after Nate confronted him about their apparent past together, having apparently teamed up to fight Galactus) while politely lecturing them on why their powers wouldn't work on him before apparently throwing the fight. Norman Osborn, a man known for underestimating his enemies if anything, considered him capable of going toe to toe with the Sentry.
When he later returned in Uncanny X-Men (2018), with his powers restored (and boosted), he effortlessly imprisoned Apocalypse and kept Magneto on a psychic leash, before casually mopping the floor with entire teams of X-Men (including his mother, mentioned above, Psylocke, Storm, and Iceman), crushing Legion in psychic combat in approximately five seconds, and later taking on all of the X-Men, plus Apocalypse and Magneto, while carrying on a conversation with Jean in his head, and then creating the Age of X-Man.
Jean Grey from X-Men is arguably just as good a candidate as Susan and Nova, and probably isn't considered such because everyone's forgotten that she started out much the same way as Susan, with limited telekinesis. As time went by, her telekinesis got stronger, she developed telepathy and began to become more powerful. The Chris Claremont got his hands on her, The Dark Phoenix Saga happened and even after her resurrection, Jean was an incredibly powerful psychic, only possibly exceeded by her 'children' Rachel Summers and Nate Grey, before dying (again) and becoming the White Phoenix of the Crown, capable of holding the entire universe in her hands. Even following her resurrection and loss of the Phoenix (or more accurately, telling it quite firmly to take a hike and leave her alone), she's still one of Marvel's most powerful psychics, going toe to toe with Cassandra Nova and being one of the very people even approximately in the same weight class as her son, Nate, when he's back at his full strength.
Storm from is an interesting example; she started off as a fairly strong Claremont Woman, but a bit unsure of herself. After some time with the team and a radical makeover in Japan, however, she became less an African Proper Lady and more of an ethnic Action Girl. She still used Spock Speak, however, and continues to do so to this day. Also, when it comes to her claustrophobia, finding herself in an enclosed space went from "instantly paralyzed by post-traumatic flashbacks to her parents' death" to "really uncomfortable, but the desire to get the hell out makes her all the more motivated to get the job done."
It happens with anyone from X-Men, perhaps due to the 'school' theme. When a character is first introduced, he or she will be able to use his or her power in its most basic, obvious form (shoot Eye Beams, make stuff fly around, etc.) but as they get better and better at using it, power and proficiency will increase, as well as the ability to make the Required Secondary Powers work for you. Next thing you know, the girl who can walk through walls is standing on air*It's never explained why an Intangible Man doesn't fall through the floor, but you can use the ability to do so even if not on an actual floor. "Down" is what you make of it, as the floor wasn't what was holding you up before you stepped off of it. By pretending she's on stairs, Kitty can even walk into the air. while threatening to make an intangible object tangible while inside your skull, or the guy who can make ice proves what a person who truly has control over water and temperature can do.note And his greatest feats are not his maximum potential, which is said to be on par with Phoenix. If anyone's existed longer than ten years, you'll barely recognize them in their first appearances. Even Nightcrawler once had a much shorter range, ran out of energy for teleporting quicker, and taking passengers was an extremely dangerous and extremely agonizing strain.
X-Men villain Apocalypse debuted in an early X-Factor arc as a fairly generic mutant terrorist with inconsistent powers and an annoying tendency to refer to himself in the third person. He's also defeated pretty easily. Cut to X-Factor Vol. 1 #18-19, the big man returns with a beefier physique, a more intimidating demeanor, and an elite mutant guard known as the Horsemen of Apocalypse. Add in some backstory and the creation of Archangel, and the rest is history.
The X-Men/New Mutants/X-Factor/Excalibur/X-Factor (again)/X-Force/X-Factor (for a third time) character Wolfsbane seems to have this intermittently, from killing someone and beating up Feral in the original X-Factor series to eating her father and clawing up Mortis' throat (with an accompanying SHRRIP! sound effect) in X-Force, and now she's been given some Asgardian powers to help her survive the Asgardian wolf baby in her stomach. She tends to veer wildly between taking this trope to heart and being The Woobie.
Fellow New Mutant member Cypher underwent some severe level-up after coming Back from the Dead. Originally, his mutant power was "read and understand any language", meaning he was simply an Omniglot when he died in the 80s. Revived in the 2000s, we learn that "language" includes "body language", meaning he can predict his opponents' moves and actually held off all his old teammates single-handedly. It also includes computer language, making him an imminently skilled hacker and programmer, as well as letting him "read" the structure of a building and discover the easiest way to destroy it.
Cypher could do the computer language thing prior to his death - but it's much more impressive now. Cypher just debuted a decade or so too early.
The Squadron Supreme are usually below most Avengers teams in power level. But in Heroes Reborn (2021), the Squadron are all-powerful Physical Gods who easily beat the likes of Galactus, Thanos, the Celestials, Knull the Symbiote god, Mangog, etc. using mostly brute force.
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