As a pivotal character in the Marvel Universe, Wolverine doesn't have many weaknesses. Razor sharp, animal-like sense make him keenly aware of oncoming attacks, superhuman physical strength helps him fight off enemies, and adamantium claws give him powerful weapons to draw on at a moment's notice. He's a one-man army with fierce temper and almost reckless regard for anyone but himself, but there wouldn't be much to his story and character arc if he was completely invincible. He's a complex character with many of the doubts, inhibitions, and issues that everyone experiences. Human flaws are what make comic book characters believable and connect them with the audience in a personable, relatable way.

Born out of need for an anti-hero, Wolverine first appeared as a solo comic in 1988. Several films and comics have attempted to explain what drives and motivates him to fight the good fight. His fear of evil destroying human life seems to be a big one. In X-Men Origins: Wolverine, he leaves Major Stryker's Team X and rejects his brother Victor (Sabretooth) because of Stryker's villainous drive to use mutants for evil in the military's Weapon X program. Later, in The Wolverine, Woverine saves a Japanese office from the atomic bomb in Nagasaki, even though Wolverine is a POW and the officer is his enemy. Whether it's external foes like Sabretooth or internal insecurities like finding love or taking care of a child , Wolverine's fears are what make him realistic. Let's take a look at some of of the other things that scare Wolverine and show that despite his intimidating demeanor, he's still a fraidy cat inside at times.

15 MURMASA BLADE

Two Muramasa Blades have been known to exist. The first, known as the Black Blade, was forged by Muramasa himself centuries ago. Those who wield this blade acquire many of the physical attributes contained within it. Unfortunately, the wielder will also be slowly driven into madness as the power of the blade consumes them.

The second Murmasa Blade was created specifically for Wolverine. Muramasa crafted this one for him to avenge his wife’s death. Wolverine’s fear of the Muramasa Blade stem from his knowledge that the blade is almost indestructible able to withstand strong blows from his powerful Adamantium claws.

14 FLYING

Although Wolverine’s fear of flying isn’t referenced in his comic books or previous films, actor Hugh Jackman felt like he needed to make up a fear for his character for the movie Logan. Jackman didn’t want to play a character that isn’t afraid of anything, and he felt like a fear flying would be a realistic one since it’s unnatural for animals to fly.

Director James Mangold seconded that notion, and suggested that Jackman’s idea could actually be canonical, since it resembles Wolverine’s known fear of water. Mangold also loved the way Jackman played the character, and thought the subtleties of flying as a fear made Wolverine separate from Batman, who’s also a dark, mysterious, and rebellious character.

13 BEING ALONE

Working as a logger in Canada meant long days outside in harsh conditions for Logan. He countered this by building a tough exterior and avoiding making friends or bringing others into his world. His reactive nature also makes him a danger to others, so Wolverine lives alone and rides solo for much of his life.

But, in the absence of company, Wolverine’s demons also emerge. He’s been known to be a heavy drinker, often smoking cigars and hanging out in seedy bars into all hours of the night. His insecurities about himself and his abilities make him not only weary of others, but afraid of what he could do to those close to him by accident if his powers ever get out of control.

12 CYBER

Cyber is one of Wolverine’s deadliest foes, first appearing in comics in 1985. With retractable adamantium talons laced with hallucinogens in his fingers, Cyber is able take down Wolverine before his healing powers are able to kick in. These claws are made of almost indestructable material, making them capable of cutting through just about anything, except Wolverine’s adamantium body and Captain America’s shield.

Cyber also possess psychic abilities and is able to track brain waves across great distances, giving him an advantage over Wolverine. And, while Wolverine was able to take Cyber’s eye out in close proximity, he has a military background and extensive hand-to-hand combat training. Deadliest of all is his pacemaker, made of the one radioactive element that’s like Kryptonite to Wolverine: carbonadium.

11 SOCIETY

As a mutant, Wolverine has never really fit into society. People attack what they’re afraid of, and they’ve attacked and tried to force mutants into hiding since comics were invented. Wolverine lives in the constant fear of being attacked by his enemies (namely Sabretooth) so he’s on guard all the time.

However, there must be something about social situations that he’s drawn to. He prefers to drink in bars rather than at home alone, which suggests he wants to interact from a distance. He’s constantly depicted as a rough loner, sometimes leaving the X-Men or simply disappearing when things get hard. Perhaps his reclusive behavior can be attributed to his father’s death when he was a boy. Without a father figure in his life, Wolverine became a rebel who doesn’t take authority or society very well.

10 FLASHBACKS/DREAMS

In 1991, Wolverine fans were finally given proper origin story via Barry Windsor-Smith’s "Weapon X" storyline in Marvel Comics Presents. The comics explain that Logan was captured in Canada and subjected to government experiments, including bonding his skeleton to adamantium in a painful process that Wolverine recounts over and over throughout his life.

The flashbacks are relived on film in X2, then X-Men Origins: Wolverine, and finally X-Men: Apocalypse. As he screams out in anguish, Wolverine can’t shake the memories of being held in captivity against his will. The storyline explains why he becomes a loner, develops a drinking problem, and basically goes crazy, no longer able to control his temper or trust others

9 THUNDER AND LIGHTNING

Like many animals, Wolverine can sense changes coming in the atmosphere. His powers give him the ability to be highly resistant to extreme fluctuations in weather, which explains why he’s been able to survive in the unbearable cold of the northern Canada with minimal supplies. One of the drawbacks of his animal instinct, however, is that he’s afraid of storms.

This one might be a bit more speculative, but there’s some evidence of Wolverine’s fear of thunder and lightning. In Incredible Hulk Vol. 1 #340, Hulk’s thunder claps are deafening to Wolverine due to his heightened sense of hearing. Also, the second Silver Samurai has an electromagnetic suit of armor that defends him from Wolverine’s attacks.

8 AMNESIA

Without a definitive backstory, Wolverine’s history was as mysterious as it was intriguing in the early years. He’s suffered from amnesia since his experience in the Weapon X program, so he couldn’t remember how his body came to be made of adamatntium, why he periodically launches into fits of rage, or why he suddenly had a heightened sense of smell and hearing.

Amnesia is also what drives Wolverine. He’s desperate to learn more about his past and to find the culprits who caused his psychological damage. The twist is that Weapon X also planted false memories in Wolverine’s consciousness using telepathy, leaving him to constantly experience flashbacks and question what memories are real and which ones are made up.

7 HIS CLAWS COMING OUT

A little known fact is that Wolverine’s hands bleed every time his claws come out, but it’s not so obvious due to his ability to heal himself. When talking about his claws coming out, Wolverine mentions in the first movie X-Men that “It hurts every time."

Fast forward to almost two decades later. Laura, the young girl Logan is fighting to help in Logan, also has the ability to draw out adamantium claws at a moment’s notice. Her bloody knuckles can also be seen as she’s driving with Logan. After all, the adamantium is fused to both characters’ bones, so it’s bound to be an anguishing experience when the claws piece through a layer of skin to come out.

6 AGING

Before the "Death of Wolverine" storyline, Wolverine never had to worry about aging or dying due to his healing powers and ability to regenerate any part of his body. He also had the energy and youthfulness of someone in their 20s even though he was over 100 years old.

However, in Death of Wolverine, his healing ability is lost and he’s suddenly faced with the tangible and scary idea that he could perish during any fight. This made him vulnerable to all of his enemies, who were now gunning for his head. The idea of being mortal proved to be a real struggle for Wolverine, and he ultimately succumbs to suffocation from adamantium hardening to his body.

5 SABRETOOTH

Victor Creed, aka Sabretooth, is almost his doppelganger in many of the ways that make Wolverine a powerful fighter. Sabretooth also has a heightened sense of hearing and smell and also has the ferocity of a wild animal.

But there’s one thing that gives Sabretooth an advantage over Wolverine: size. Sabretooth is a massive beast, towering well over 6 feet tall and almost 300 pounds. Wolverine, on the other hand, is a meager 5’3 with less than 200 pounds on him (probably over 300 with the adamantium skeleton). Sabretooth also uses the element of surprise to his advantage, attacking Wolverine in the chilly Canadian forest in X-Men Origins: Wolverine.

4 LOVE

logan and xavier

In Logan, Wolverine is put in the impossible position of having to take care of two people: Charles, who has a brain altering illness, and Laura, a young female mutant whose powers strongly resemble Logan’s own. Having never had to worry about anyone but himself, this position makes Logan very uncomfortable and he initially resists getting close to either of them.

On the romantic relationship side, Wolverine’s fear of love probably stems from the heartbreak he felt by losing his first love, Jean Grey, who first appeared in X-Men #1. After Jean Grey perishes and becomes Phoenix, Wolverine never gets over their initial love and it only becomes worse once he’s forced to bury her over and over again.

3 RESPONSIBILITY

logan-laura-dafne-keen-x-23

Logan is also a great example of Wolverine’s resistance towards taking on responsibility, especially when it comes to having a family and/or children. When Logan meets Laura, he’s not interested in helping her, originally because he doesn’t want to be responsible for a child, but the audience later realizes it’s also because he’s not sure how to handle his connection with her.

He begrudgingly agrees to drive her to Eden, and during the rest of the film, the audience comes to see him as a father figure with real fears about raising a daughter, just as all fathers have in real life. He also feels a sense of responsibility to Charles, perhaps because of all of the good things the professor has done for him throughout his life.

2 CABONADIUM

Carbonadium, a radioactive metal that was created in the USSR, is just as strong as adamatium. It’s also flexible and cheap to produce. The substance first appeared in X-Men Vol. 2 #4 when Russians attempted to create their own version of adamantium. The result was the fatal coils that Omega Red, another product of the Weapon X program, uses in his coils.

In Deadpool Kills the Marvel Universe, Deadpool’s katanas are also laced with the deadly material. Carbonadium is said to destroy the healing powers of mutants, essentially making it Wolverine’s kryptonite. It’s the one substance that can end him -- outside of the "Death of Wolverine" storyline, that is.

1 DROWNING

Drowning is well documented as being one of Wolverine’s worst fears. Not only is his adamantium-lined body less than ideal for swimming, but his healing powers are virtually useless when he’s under water.

In the two-part story "Drowning Wolverine", the titular hero is stuck underwater which permanently damages his ability to heal himself. As a result, Wolverine is left susceptible to viruses, injuries, and aging. Wolverine’s drowning fear is further explored in X-Men: Days of Future Past, when Magneto picks him up and launches him into a lake, leaving him to drown. Despite his animal instincts and gruff appearance, water is clearly the one thing that terrifies this cool cat.