The Marvel comic universe is shockingly expansive – even to the fans who have been following it for ages. There are countless characters to love and follow, and even more secondary and tertiary characters running around in the background.

What may come as a surprise is hearing how many characters are doctors as well. In this instance, we don't mean Ph.D. holders (that would make this list even longer!), but true experts of medicine.

RELATED: Doctor Doom: 5 Things We Like More About The 2099 Version (& 5 That We Don’t)

When we think doctors in Marvel, a few names come to mind right off the bat. But this list is going to include more than them. We hope you enjoy this enlightening piece, and at least now if you ever get stuck in the comics, you'll know a doctor or two that'll help you with your inevitable injuries.

13 Karlin Malus

Dr. Karl Malus has always been fascinated with superhumans, thanks to the dramatic adventures of the Fantastic Four. He began working at a lab known as the Institute for Superanormality Research, which he ran – and named. He has a bad tendency of tinkering with some of the worst characters that Marvel has to offer, with predictable outcomes. None of this helped him garner a positive reputation - as a person or as a doctor. Hence why he's the last character to make the cut.

12 Mister Sinister

Next up on the list is Dr. Nathaniel Essex, who became Mister Sinister thanks to the research he personally participated in. As a biologist, he was determined to crack the human genome and create his own mutation (using the Essex Factors).

With a little help from other Marvel characters, Mister Sinister was able to come to fruition, alongside several noteworthy abilities. There's the usual superhero enhancements (strength, reflexes, speed, etc), as well as telepathy, telekinesis, and more. Unfortunately, like many others on this list, Mister Sinister has squandered his talent, putting him towards the bottom of this list.

11 Karla Sofen

Dr. Karla Sofen is another Marvel character with a psychiatry focus. Her mentor found himself on the wrong side of Captain America, it sort of set the tone for the rest of her career. Using her knowledge, she 'borrowed' abilities from Moonstone and masqueraded under that mantle for a time.

After her plan was revealed, she changed plans. Later she joined Egghead and the Masters of Evil. She has consistently used her intelligence to go against Avengers and other heroes. It really is a shame, considering that Sofen really could have helped the world, had she bothered to try. That reason along ranks her fairly low on the doctor scale.

10 Curtis Connors

Dr. Curtis Connors is one of the more visually iconic characters. He's also known as the Lizard, and it's pretty obvious why. While that is what he is best known for, he also has two doctorates in biology and biochemistry.

RELATED: 10 Marvel Villains Who Are Actually Smarter Than Doctor Doom

As with many a Spider-Man villain, he has a long and complicated history to go with this tale. His frequent appearances keep him in the minds of fans, but that isn't helping his ranking as a doctor any.

9 Victoria Montesi

Victoria Montesi from Marvel Comics

Victoria Montesi is the daughter of Vittorio Montesi. When she turned against her father's wishes, she became an outcast. So instead she became a doctor. Though things aren't quite that simple. The man that raised her (mostly) is not her true father, but Darkhold is. Since the truth came out, she's been working on resisting him, alongside others who hold the same beliefs.

Credit to Victoria, she's at least made a strong attempt at helping the world around her. Much like one would expect a doctor to do. That's why she's earned herself a decent spot on this list.

8 Donald Blake

Thor Donald Blake

Donald Blake is the persona that Thor took upon himself when he needed to find a life for himself on earth. With a little bit of help from Odin, Dr. Donald Blake became more than just a persona, and eventually became his own entity.

This is the persona that fell in love with Jane Foster, though later Thor followed suit as well. While he was on earth, he was considered to be one of the best doctors and surgeons around, second to only a few other named Marvel characters. Donald Blake became known as a man of healing, and a man willing to help those around him. He was a solid doctor, even if his past did complicate things a bit.

7 Doctor Druid

Next up on the list is Anthony Druid, aka Doctor Druid. He is both a doctor and an expert in Druidic magic, making him unique even among his peers. He even has the arrogance to go with that (sound familiar?).

Doctor Druid's specialty was psychiatry, though recently he's been portrayed as working at the very same hospital as Doctor Strange – the irony is not lost on either doctor here. Doctor Druid may be cocky and arrogant, but he's still extremely intelligent. His latest appearance in the comics proves his willingness to once again use his intelligence to help others.

6 Fazia Hussain

Dr. Fazia Hussain is most famous for her alter ego, Excalibur. Though she's hesitant to accept the name herself. Her powers and knowledge grant her unique abilities, most famously Living Cross-Section, which is exactly what it sounds like. She can disassemble anything (people included, as she learned the hard way). Thankfully, she can also reassemble them.

While Fazia may not love the name she's most commonly remembered by, there's no doubt that she is a figure of good. She holds true to all of the oaths she's made, including those of a doctor. Earning her a higher spot on this list.

5 Cecilia Reyes

Cecilia Reyes

Dr. Cecilia Reyes is an incredibly talented trauma surgeon, one who cared more about saving lives on the table, than picking up her identity as a mutant.

RELATED: Marvel: 5 Times Benedict Cumberbatch's Doctor Strange Was Comics Accurate (& 5 Times He Wasn't)

Later she did cave and go help the X-Men, as they needed somebody with her particular skill set. Dr. Reyes has spent her whole life helping others, from her time as a trauma surgeon to her time with the X-Men. No matter how one cuts it, she's a talented doctor who has saved countless lives.

4 Leonard Samson

ty-burrell-leonard-samson-incredible-hulk

Once upon a time, Dr. Leonard Samson wanted nothing to do with psychology. A bit ironic, since he ended up getting his degree, just like his father (and namesake). For a time he worked under General Ross, which eventually resulted in him having access to radiation put off by the Hulk. A temptation he could not resist. Since then he's had a long history in Marvel, both as a doctor and as a Hulk. Though sometimes he did lose the latter status.

His career as a psychologist in the superhero world has gotten him a lot of attention. Even though he doesn't always make the right decisions when the Hulk is involved, the intent to help is still there. Not to mention the brilliance, earning him a place near the top of the list.

3 Linda Carter

Dr. Linda Carter, aka the Night Nurse, is one of the more famous Marvel doctors. Mainly because she is solely that: a doctor through and through. She runs a clinic specifically for the superheroes in need of a doctor they can trust. As one might imagine, she has proven vital on more than one occasion. Even despite the jokes around her name, and the fact that she's actually a doctor.

There's no questioning Linda Carter's place on this list. She is literally the doctor that superheroes (and sometimes villains) rely on. She helps others, no questions asked. She's put her life on the line on more than one occasion, all while keeping the heroes under her care alive.

2 Jane Foster

Natalie Portman as Jane Foster in thor

Jane Foster is another legend in both Marvel and the medical world. Originally she was a nurse working alongside Dr. Donald Blake, but she did eventually become a doctor under her own right. She's also picked up the mantle of Thor, followed by becoming the last Valkyrie.

Unfortunately, all of that saving the day has cost her a bit in terms of her career. She's currently acting as an assistant in the hospital morgue, but at least it gives her a bit more freedom. While her career in the medical world may be taking a downswing at the moment, there's no doubt that the intelligence and willingness to help is still there. In fact, that is exactly the problem with this doctor. She cares too much, and is trying to do too much in order to help. That earns her one of the highest spots on the list.

1 Stephen Strange

Stephen Strange Doctor Strange

Last, but certainly not least, there's Doctor Strange. He's probably the most famous doctor on the list, with renowned skills and intellect. He became one of the best, if not the best, neurosurgeons around.

That is, until the accident. He was in a car accident that failed to take his life but did damage his hands beyond repair. This put him on the path fans know him so well for becoming the Sorcerer Supreme. It's obvious that Strange earns the top spot on this list. He's the best-known doctor of the Marvel universe, as well as arguably the most talented. His knowledge seems to know no bounds, and he has consistently found a way to help others. Even if it wasn't the path he planned to take for himself.

NEXT: Doctor Strange: 5 Costumes That Made Him Look Cool (& 5 That Were Just Lame)