Having blood on your hands is a feeling that defines many heroes and villains. However, there comes a time when one is so far gone that ending more lives doesn't even faze them -- they might even get some enjoyment out of it. It's times like these when everyone in the world is in danger and millions of lives are immediately put at risk. This kind of evil often concocts the most dastardly of plots that require the greatest amount of effort from heroes in order to take down. No matter how bad of a beating they take, they'll be determined to come back and cause more chaos. They'll be eager to take more lives and fill the Earth with blood or watch it burn.

RELATED: 16 Marvel Villains Who Would DESTROY The Justice League

In comic books, we've seen this happen over and over again. Some of these villains get so dangerous that they've destroyed millions of people without batting an eye. Perhaps they're trying to impress someone. Maybe they believe they're liberating the world. Whatever the reason may be, these are the characters we'll be looking at today. Get the Avengers, Justice League, and every other superhero team on speed dial, because we're looking at 15 villains who shockingly murdered millions.

15 THANOS

Kicking off this list is the Mad Titan himself. This cosmic being had a pretty rough life growing up, which culminated with him falling in love with Lady Death. In order to impress her, he believed that he had to take to the cosmos and destroy all life in the universe.

This led him to take possession of the Infinity Stones in the Infinity Gauntlet miniseries. He then used their power to wipe about half of the Marvel Universe, including most of its respective heroes. Who knows how many bodies he racked up in that time? Whatever the count, it was big enough to bring all of Earth's heroes together to fight Thanos, and even then, he still killed most of them on the spot.

14 ANTI-MONITOR

After DC had been going on for several years, they were troubled because of how massive their continuity had become. Newer readers were going to have a harder time keeping up with all of the events. Because of this, they felt it necessary to rework their canon and wipe the slate clean. They did this by introducing the Anti-Monitor in Crisis on Infinite Earths.

Due to this massive being trying to recreate the world in a different image, all of DC's finest banded together to stop him. However, the war was too strong, and many of our favorite heroes lost their lives in the struggle (like the Flash and Supergirl). The Anti-Monitor is also responsible for the destruction of multiple worlds, racking up his kill count to unthinkable numbers.

13 NEKRON

We all know the story of the Lanterns of the DC Universe. Each embodying a different attribute, they fight for their own purposes, some trying to protect it, and others trying to rule it. However, in the Blackest Night, it was revealed that there was another Corps waiting to come to Earth and conquer it: The Black Lantern Corps.

Led by the being known as Nekron, he raised all of the dead to fight for him as Black Lanterns, against all the other Lantern Corps. But that's not the reason he's on this list. He continued to add to his army by killing heroes they fought and handing them Black Rings. Heroes who also died in the past were receiving these rings as well, instantly turning them into decaying zombies.

12 GORILLA GRODD

Gorilla Grodd is one of the most brilliant and most savage Flash villains to date. Being horribly treated and abused as a regular gorilla, he slowly gained the intelligence beyond humanity and decided that all of mankind deserved to die. His goal at that point shifted to destroying all traces of humans and ruling over the Earth.

As you can imagine, Grodd hatched many schemes to rid the world of humans. He didn't care which man got in his way; they were all subject to die. In Son of Ambush Bug #5, he even attempts to kill humanity by stopping the evolution process from even happening. Thankfully, the Flash is usually there with some quick thinking to deal with Grodd as the occasion calls for it. However, as we've seen in Injustice 2, he doesn't go down so easily.

11 GREEN GOBLIN

Norman Osborn wasn't always a psychopathic killer, but the Goblin persona has been a part of him since he was a young boy. After being abused by his father, he knew that he wanted to turn out differently and take control of his own life. His first act of exercising control, however, was killing his pet dog.

From that point on, Norman Osborn was never right in the head. When he needs to take a life to suit his needs, he does it. Over the years, he has slain so many people. He killed Gwen Stacy, Spider-Man's first real love. He murdered nearly an entire organization known as the Brotherhood of the Scriers (who first appeared in Amazing Spider-Man #417) just to rise in the ranks, and he's taken out plenty of superheroes in his day.

10 GALACTUS

The cosmic beings of the Marvel Universe are rarely there to benefit the Earth, and Galactus is just further proof of that. Being one of the oldest entities, he feels entitled to do as he pleases, especially considering the fact that he is motivated by one of the deadliest hungers: A hunger that can only be satisfied by consuming planets.

While he, at first, consumed planets light years away, he eventually set his sights on Earth in Fantastic Four #48. Since then, he has been a constant thorn in Earth's side that usually takes all of Marvel's greatest heroes to fight. Considering that he has eaten many planets over many years, there's no telling how high Galactus's body count is. We can tell you that the only one who could top it in the Marvel Universe is probably Thanos.

9 THE JOKER

"Some men can't be bought, bullied, or reasoned with. Some men just want to watch the world burn." Fewer words have never been more true about the Joker. Since his creation, there's been a sinister joy about the Clown Prince of Crime. He kills just anyone he pleases in the most elaborate and enjoyable ways possible.

In The Joker: Devil's Advocate, he claims that he took the lives of around 2,000 people, but after reading all of the comics and seeing all of the depictions of him, we'd wager that it was much more than that. In Injustice, he blew up the entire city of Metropolis, as well as killed Lois Lane and the unborn child of Superman. Once you start adding alternate universes, the numbers keep climbing. What makes this worse is to imagine how many he would kill if Batman didn't exist.

8 SUPERMAN (INJUSTICE: GODS AMONG US)

Speaking of Injustice, it would be remiss of us not to mention the tyrant that Superman was in that universe. After Lois and his child were both killed by The Joker, he murders the Clown Prince of Crime and then decides to rule the world to prevent more deaths from happening. Unfortunately, he becomes a brutal dictator and kills many more people after that.

Among the many deaths he caused, Superman was responsible for destroying the entire planet of Oa along with the Green Lantern Corps. That's not even where it ends. Superman is also responsible for killing other various heroes, even those who merely disagreed with his methods (may you rest in peace, Billy Batson). It took the intervention of a Justice League from a different universe in order to deal with the Man of Steel.

7 NITRO

One look at the name and you may not be sure who Nitro is. However, you'll remember his name once we describe what he did. Jump back to the opening moments of the Civil War event. Speedball and the New Warriors were shooting a TV show where they decided to fight a criminal team. While they seemed to be fairly harmless at first, it wasn't long before one of them, Nitro, showcased his power.

Using his explosive abilities, he set the entire city of Stanford ablaze, killing anybody in the area and decimating the city. All of the Avengers showed up to help with the tragedy, but there wasn't much that they could do. It's estimated that Nitro killed thousands including around 60 children who were riding in a bus when the event occurred. No wonder this one move began an entire Civil War.

6 THE PUNISHER

After Frank Castle was basically screwed out of his family and everything he loved, he decided that the world would be better off without evil in it. Instead of taking a classic superhero approach and locking them up, he took the role of judge, jury, and executioner by killing them where they stood.

Having the utmost military training, the Castle knew how to kill anyone with just about any weapon (including his fists) and we've seen him kill time and time again. According to Stephen Wacker, an editor of the character's comics, the on-again/off-again hero has amassed 48,502 kills since his first appearance. That's even without considering his appearance in issues like Punisher Kills the Marvel Universe and Punisher MAX. If you can't tell by the names of those comics, he's killed a lot.

5 ULTRON

Does it come as any surprise that one of the Avengers' greatest foes also has one of the highest kill counts in the Marvel Universe? After being built with the intelligence of Hank Pym, Ultron became autonomous and decided that humanity wasn't worth saving and that AI should rule the world instead. He went about slaughtering humans and heroes just to get a taste at being a ruler.

Ultron would later receive his own event in the form of Age of Ultron that saw him taking over the entire Earth, having killed millions of humans in the process. While the story takes place in a different universe, Ultron is responsible for many deaths in Earth-616, and we fear him anytime he shows up (save for Avengers: Age of Ultron).

4 CARNAGE

If there were ever a Marvel Universe equivalent to The Joker, it would be Carnage. Cletus Kasady started his life as a psychopathic killer who murdered his grandmother by pushing her down a flight of stairs in Carnage Vol 2 #12. From then on, he's caused numerous problems like torturing a dog and burning down the orphanage he stayed at.

After bonding with a symbiote in prison, Kasady became known as the deadly Carnage. He escaped from his cell and went on a citywide killing spree immediately in Amazing Spider-Man #361. Since then, Carnage has always killed for fun and used his newfound powers to deal as much damage as possible before he got the attention of superheroes like Spider-Man and Venom. Anytime Carnage begins operating, it requires a great amount of strength. However, he's easy to find, as he leaves a trail of bodies wherever he goes.

3 DOOMSDAY

Doomsday was a being created for one purpose: to destroy. After being reborn and gaining strength over and over for many years, Doomsday ended up murdering his own creator and traveling the galaxy. He then ended up on the planet Earth, where he engaged in a brutal fight with Superman. As they battled, Doomsday destroyed many buildings in the process, leaving an unknown level of death in the process during the "Death of Superman" storyline.

This beast of a villain has returned numerous times in DC's lineup only to cause all sorts of destruction. Considering the fact that he has also been in other dimensions and on other planets, one can only assume the amount of deaths that he has caused. Quite frankly, we'd much rather not think about it.

2 OZYMANDIAS

Watchmen has all kinds of interesting characters and themes to think about, and that remains true for the villain, Ozymandias. His ultimate scheme is to get the people of the Earth to unite by allowing alien invaders to come and wreak havoc. That way everyone would unite under one banner and stop warring with one another.

While he has good intentions, Ozymandias's plan caused the deaths of millions in the process (yes, his plan worked). The Watchmen tried to stop him but to no avail. This calm and intelligent supervillain was always three steps ahead, and the result was both a united nation and a pile of bodies to bury at the end of the day. However, he believes that the needs of the many outweigh the needs of the few. It's just a small price to pay to get the world working together.

1 BOLIVAR TRASK

You would think that in a contest of kill counts, someone like Bolivar Trask wouldn't be too high on the list. However, you factor in that he was the man who created the Sentinels to hunt down every mutant alive, and you begin to put two and two together. He created these robots as a means of defense for the humans, as he feared that mutants would conquer them (something that was shown in X-Men Days of Future Past).

However, the Sentinels proved to be much more effective than any of us imagined. As of X-Treme X-Men #37, it was revealed that Trask's Sentinels had killed over 16 million people since they were created. While that does include human deaths, they only account for a few hundred thousand. Trask's army has been on a killing spree since they were created, and they're a force to be feared.

Did we miss any other comic book mass murderers? Let us know in the comments section!