For various reasons, some superheroes hold back. Some are afraid of hurting a civilian, some don’t want to become that which they hate, others are crippled by self-doubt. Regardless of why they hold back, they remain heroes of the highest calibre, even if those self-imposed limits prevent them from becoming all-powerful.

A recurring side-effect of using one’s full power is becoming corrupted by it. To quote Lord Acton, “Power corrupts, and absolute power corrupts absolutely.” When some top-tier heroes have fully let loose they have, on occasion, become corrupted. Some have found redemption; others have fallen to darkness.

Others are just blatantly unaware of what power they truly possess. In cases where a hero’s body has been taken over by a villain (because... comic books) they have used the hero’s powers in new and interesting ways, often exceeding the limits of what the host body believed possible. Villains, it seems, rarely hold back when dishing out the body blows.

Here are The 15 Most Powerful Superheroes Who Won’t Use Their Full Powers.

15. Zatanna

Zatanna’s limits have never fully been established, with her power set varying depending on who is writing about her at any given time. Initially, during her first adventures with the Justice League, her powers were quite limited, consisting in the manipulation of fire, air, water, and earth. As time has gone on, she has been shown to be one of the most capable sorcerers in the DC universe.

The source of her powers is apparently genetic, as she inherited her father’s gifts for manipulating magic and casting spells of intense power. As a focal point for her power, she usually says her spells backwards, but she apparently doesn’t need to do this as she has cast spells when bound and gagged.

Because Zatanna’s powers are limited by her self-confidence, she doesn’t usually use them to her full potential. After a series of errors caused her confidence to be shattered, she was rendered totally powerless for a time.

14. Captain Atom

In the New 52 continuity, Captain Atom’s powers stem from his atoms constantly splitting and reforming, giving off an infinite amount of power. Theoretically, his powers have no limits. He has been seen to transmute the atoms of lava into snow with barely a thought. Also, he has been able to enhance his physical strength to the point where he was able to beat three alternate Supermen effortlessly. He can also generate energy blasts with seemingly no upper limit.

His only weakness demonstrated so far is a tendency for his atoms to lose coherence if he uses too much power in a short space of time. This is due to his current power source being linked to Strong Nuclear Force, the energy that binds protons and nucleus in the nucleus. It is expected for him to be able to overcome this as his powers grow.

Given the enormous power at his disposal, it begs the question: why there are any bad guys left in the DC universe at all? It has been theorized that he is deliberately holding back in order to maintain his humanity. With his body having transcended basic mortality, he is holding on to his identity as a man and subconsciously fears becoming a cold, emotionless being such as Doctor Manhattan from Watchmen.

13. Spider-Man

During Spider-Man’s early years his power levels appeared to be much lower than they are today. He could be seen fighting ordinary men with ease, but struggled against more powerful enemies, being hopelessly outmatched against the Sinister Six, for example. In recent years, he’s been seen able to hold his own against far more powerful foes. He has stated many times, particularly in Dan Slott storylines, that he is able to hold his own against the Hulk.

During the “Superior Spider-Man” storyline where Doctor Octopus swapped bodies with Peter Parker and took on the role of Spider-Man, he found Spider-Man’s body was far stronger than he had ever realised. When he first took over the body, he punched the Scorpion in the face. Unaware of his limits, he took the Scorpion’s jaw clean off his face with one blow. Doctor Octopus was shocked, realising that the real Spider-Man had been holding back his full power during their many confrontations over the years.

12. Luke Skywalker

Not quite a superhero, but his many comic-book appearances over the years have earned him a place in this list nonetheless. In the original Star Wars movies, the Expanded Universe, and the new timeline established by The Force Awakens, Luke Skywalker is considered to be one of the premier force users of all-time. While many force users, particularly the Sith, have demonstrated a wide range of powers such as wielding lightning, generating enormous force-storms, and even cheating death, Luke himself rarely goes deep into the Force to use his full potential.

Like most light-side force users, Luke feels that using the force for selfish needs is a path to the dark-side. It’s not fear of becoming corrupted as such-- since fear is the path to the dark side. Rather, it is an attempt to remain pure of intention so that the force will remain in balance.

During the new timeline established by The Force Awakens, Luke has retreated from the Force after his nephew Ben Solo became corrupted by the dark side. It remains to be seen if the Jedi Master will finally dig deep and demonstrate the full power of the light-side of the Force.

11. The Flash

While the many incarnations of The Flash have had varying power-levels, the most famous version of the Flash is most likely Barry Allen, in part due to his current role as the star of The Flash TV show, so we’re concentrating on that version for now.

Barry Allen has continually been referred to as “The Fastest Man Alive,” but has already faced the Reverse Flash and Zoom, both of whom were initially much faster than him. His power isn’t just running fast, though. It’s so much more than that. Not only can he generate enormous kinetic energy as he moves at impossible speeds, which he can release in a number of ways, he can also access the “Speed Force,” which has so far allowed him inter-dimensional and time-travelling powers. Theoretically, if he could access the full range of his powers he’d be unbeatable by anyone currently in the Arrowverse.

While he continues to push himself to go faster and faster, all in the name of heroism, he does appear to be holding back from achieving the same feats as Reverse-Flash and Zoom. Could be that he doesn’t want to be like them? Or it could be that a lifetime of pain from losing his mother and his father being incarcerated for a crime he didn’t commit has left Barry with a subconscious desire to not want too much, for fear he may lose it, as he has lost so much in his life? With season 3 of The Flash fast approaching (pun intended) and the rumour mill suggesting Barry will be powerless once more, we may begin to unearth the secrets behind his limits and his connection to the speed-force one and for all.

10. Doctor Strange

Doctor Stephen Strange has, for most of his run, been considered the Sorcerer Supreme with near-limitless mystical power. He has been seen conversing with abstract entities such as Eternity and is the first mortal being to be able to do so. His mystical powers have been so great that he has been sought out by beings of enormous power such as The Silver Surfer and Adam Warlock. And yet, he holds back from using his true potential.

During Marvel's Civil War, the Watcher comments that Doctor Strange could end the conflict with a thought, implying that he has more power at his disposal than half of Earth’s superhuman population. Doctor Strange instead chose to meditate in seclusion, hoping that the two parties would come to a peaceful solution.

When the Civil War ended, Doctor Strange joined the New Avengers alongside Iron Fist, Luke Cage, and Spider-Man, and it wasn’t long before he was pulled into their adventures. During this time, he had to use more power than he was accustomed to and had to draw on increasingly dark magic. When he used the darkest magics to battle the Incredible Hulk, it came with a heavy cost. He ceased to be The Sorcerer Supreme, as he had become unworthy of the title.

He has since regained that title, but has yet to exhibit nearly the same power levels he had before. He seems unwilling to risk using his full potential, which could potentially mean that other users of dark magic may soon be a greater threat to Earth than before.

9. Havok

Havok is the brother of Cyclops, and like his brother has massive energy-based powers. Unlike Cyclops, who emits blasts of force from his eyes, Havok absorbs cosmic energy which he releases as plasma energy from his fists or chest. At his peak, his powers were said to be able to level mountains and were potentially greater than those of his brother.

Like his brother, he has to demonstrate a high-degree of self-control, otherwise he may well harm those around him. Unlike Cyclops, he doesn’t have a pair of ruby quartz lenses to hold back his power. While he has had various gauntlets over the years, they are only able to help him focus his energies, as opposed to fully contain them. For many years, he wore a black containment suit that helped him hold back his power and focused them through a gem, but over the years he has demonstrated the ability to keep his powers in check through sheer force of will. Should he ever use his powers to their fullest, he may be able to release enough energy to take down foes as powerful as Magneto with ease, but his fear of letting go may mean he'll never reach his full potential.

8. Doctor Fate

While there have been several incarnations of Doctor Fate since Kent Nelson first put on the helmet, each has possessed more or less the same power levels, due to the source of the power remaining the same.

DC's Doctor Fate, much like Marvel’s Doctor Strange, is a master practitioner of mystic arts, and as such, has the ability to call upon vast reserves of mystic power for a wide range of purposes. He has manifested typical psychic powers such as spell-casting, telepathy, and telekinesis, as well as the ability to enhance his physical prowess, giving him invulnerability and super strength.

Given his ability to grant himself near limitless abilities, the only thing keeping his power in check appears to be the will of his host. Unlike many superheroes, the body of Fate is essentially powerless, but does act as a focal point for that power. If the host body and the source of the power, Nabu, disagree on a course of action, the host can prevent Fate from going too far.

7. Cyclops

Back before he became a homicidal lunatic, responsible for the death of Professor Xavier, Scott Summers was considered to be the quintessential boy scout. Whereas his X-Men team-mate Wolverine was prepared to cross the line and kill if necessary, Cyclops was always more reserved and rarely used his powers to their fullest effect.

While many heroes, even mutants, can blend in effortlessly, with powers that are considered amazing gifts, Cyclops’ power has often been considered a curse. For years it was believed that his power couldn’t be controlled, due to a brain injury he received when his parent’s plane crashed. It was eventually revealed that his inability to hold back his optic blasts without a visor or ruby quartz lenses actually stemmed from severe psychological problems. His childhood, spent in an orphanage, had been miserable and when he developed super-powers he unconsciously repressed the ability to control them.

Even when he learned to focus his power, he almost never let loose its full potential. Once, on Arkon, the Imperion’s home world, he used Storm’s lightning to augment his power and generated a white energy blast, far stronger than his customary red one. This has, so far, been the only example of his power used beyond its limit and, due to his severely repressed nature, it’s unlikely we’ll see this power level again.

6. Professor X

Professor Charles Xavier has spent a lifetime training his students to achieve their full potential, so it’s ironic that he has imposed so many limits on his own. Xavier has one of the most powerful telepathic minds in the Marvel Universe, with only The Shadow King, Cable, X-Man, and Jean Grey seemingly in the same league. Even without augmenting his power through Cerebro, he has been able to control multiple minds at once, communicate over vast distances, and even wipe minds utterly.

However, Xavier’s psyche has a dark side to it. A phantom apparition resembling him struck out at the second generation of X-Men early in their career. He was under intense pressure and the side of his mind that he represses broke free temporarily. It was subdued, but many years later another repressed dark side came forth in the form of Onslaught. Onslaught was the total range of Xavier’s power personified, blended with the darkest parts of Magneto’s mind from when Xavier wiped Magneto’s mind clean. Again, this side to him was destroyed, but it took the sacrifice of dozens of heroes to do so.

While Xavier is currently deceased, he has come back from the dead before. Should he do so again, it’ll be interesting to see what at level his powers will come back and whether or not he will return as a benevolent being, or a merciless one.

5. Iceman

The quintessential class clown, Bobby Drake was one of the first X-Men and the youngest of the first generation. To begin with, his powers consisted of little more than being able to appear as a snowman-type being and freeze the air around him. As time went on, he developed a hard ice-shell around him and learned to generate ice-slides to quickly transport himself. This remained his power level for many years, despite there being hints that he was capable of more if he applied himself more fully.

During his time with The Champions, he trained with Black Widow and Hercules to develop hand-to-hand skills, but his power levels remained the same. When Emma Frost, the White Queen, took over his body she used his powers in ways he had never dreamed of. She transmuted his body into ice, merged with a river and transported herself many miles in a few moments, froze the molecules of other people, and even turned into a mist-like form. When Bobby got his body back, he asked her to train him, but she refused.

Eventually Bobby became far more adept in his powers, but hasn’t ever been able to use his full potential, in part because he was repressing his sexuality. Recently, he met a future version of himself and learned that he has powers he hasn’t even dreamed of yet, indicating that there is still much more potential in Iceman than we have ever seen.

4. Franklin Richards

Franklin Richards, the son of Mister Fantastic and the Invisible Woman, is potentially the most powerful being in existence. He has the power of a god in the body of a small boy. While still a toddler, he developed a range of telepathic powers that Mister Fantastic realized were highly dangerous and tried to deactivate until Franklin was older.

When still a young boy, the Onslaught incident happened. Onslaught sought to increase his own powers by adding the telepathic powerhouse X-Man and young Franklin to his gestalt form. Franklin’s latent reality-warping powers were used by Onslaught to hold off the combined might of the X-Men, Avengers, Fantastic Four, and the Hulk for quite some time. Eventually the heroes were victorious, but at the cost of their own lives. Franklin, reaching out subconsciously, used his powers to create an alternate reality for his family and their allies to reside in. This act of godhood attracted the attention of the race of space-gods known as the Celestials who felt that Franklin’s powers rivalled, and possibly surpassed, their own.

While Franklin’s powers have been burned-out, they've been seen to be restored in recent years. While the Fantastic Four are currently on a break, when they do return to publication, young Franklin’s powers could well be the ultimate factor in deciding the fate of the universe once more.

3. Superman

Few people have to pull their punches quite like Superman. Often quoted as being "Faster than a speeding bullet. More powerful than a locomotive. Able to leap tall buildings in a single bound,” his power set is, in fact, far greater. One of the most powerful beings in the DC universe, he tends to have to exercise extreme caution when doing the most mundane activities, such as opening doors, lest he rip them clean off their hinges.

Only when he’s had to face off against some of his most powerful physical opponents has he been able to truly let loose, and even then he has to be careful not to level a city and injure civilians. While villains such as Darkseid, Mongol, and Doomsday can match, or exceed him, blow for blow, his wide-range of powers often gives him the edge, with his flight and heat vision giving him a wide range of tactical advantages. However, he has found, to his detriment, that Darkseid’s eye-beams are far more dangerous than his own.

2. Sentry

The Sentry is one of the Marvel universe’s most powerful figures. He can match the Hulk in a fist fight, along with having enormous energy-projection abilities, and even a latent telepathic power that appears to have global potential. His inability to reach his full potential comes from his massive psychological problems. He literally manifests a separate entity known as “The Void” that undoes any good deed he commits. The greater his good deed, the greater the act of evil committed by the Void to balance the scales. For this reason, not only can he not risk achieving his full potential, he fears doing so.

When his fragile mind broke due to his existing problems, coupled with the manipulations of Norman Osborn, he took on the whole of Asgard nearly single-handedly. When opposed by the Greek God of War, Ares, he tore him in half with barely any effort. Only when the lucid part of his mind managed to regain some control did he hold back the Void long enough for the Asgardian Thunder God, Thor, to deliver a massive killing stroke.

1. Goku

Initially thought to be from Earth, Goku is, in fact, an alien, a member of the warrior race known as Saiyans, which explains his incredible superhuman strength. While often depicted as carefree and cheerful, he is an incredibly dedicated warrior and drops into a more serious mind-set when in combat. His martial arts skills are so deeply honed that he is able to focus his Ki and use it to generate an energy-based attack that manifests as a blue energy blast from his hands.

This one might be semantics, but Goku's refusal to face threats with his whole strength until he feels like it'll be interesting mean that he rarely uses his full potential, preferring the fight over anything else. He once refused to fight Cel at full power, preferring to fight at a lower level just to keep things interesting.

With few in the Dragonball-Z universe able to match him, Goku is unlikely to ever use his full potential on a regular basis.

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Note: while we did consider adding the Hulk, as Banner holds back from joining the fight even though he knows he’ll win, we considered Hulk and Banner to be separate entities.

Got a theory you’d like to share? Think One-Punch-Man should have made the list and can make a case? Let us know in the comments!