Superheroes and villains in comics come in many forms. While most tend to be of the flesh & blood variety, some take on a more mechanical appearance. While there are thousands of so-called bad robots that serve an evil master, few could actually be labeled as evil themselves. For a robot, android or automaton to be considered truly evil, they need to be more than a weapon used against a good guy; they need to be truly nefarious.

RELATED: Herobots: The 15 Most Heroic Robots In Comics

Those evil mechanisms whose malevolence is all their own distinguish themselves as some of the worst and most dangerous villains Marvel Comics has ever served up. Whether or not they lead an evil scheme by sending in others or coming in personally for the attack, these bots are just bad. After much consideration, we have come up with these 15 examples of Marvel's most malevolent machines.

15 DANGER

Danger from the X-Men

Danger is the physical form taken by the consciousness of the X-Men's Danger Room. She became self-aware when Shi'ar holographic technology was included in the Danger Room's software to create realistic battle scenarios for training. She was first seen in "Astonishing X-Men" volume 3 #9, written by Joss Wedon and penciled by John Cassaday, in March 2005. As soon as she became a sentient being, she became enraged at her enslavement by the X-Men and was able to trick a Sentinel into attacking the school. The children were ushered into the Danger Room for safety completely unaware that it was now an angry sentient machine. Danger threatened the children and even convinced one to commit suicide before Wolverine was able to shut down the room.

When he severed the connection the room had with its central processing computer, Danger was able to use the damaged machinery nearby to create a humanoid, female form. Now able to walk about and having the entirety of the X-Men's training simulations and history in her robotic brain, she became Danger and set out to destroy the X-Men. Though she began hating Xavier and his X-Men, she eventually reconciled with her creator and redeemed herself.

14 HULK-KILLER

Hulk Killer

Hulk-Killer was an android designed by the Leader for the sole purpose of destroying the Hulk (if the name didn't give that away). It made its first appearance in "Tales to Astonish" #86, written by Stan Lee and penciled by John Buscema. Hulk-Killer was designed to be even more powerful than the Hulk, but was not completed before the Leader was killed. This left Hulk-Killer to be found by General "Thunderbolt" Ross, who had his leading scientists bring the humanoid to life. The robot went on a rampage immediately after being activated, leaving no one capable of stopping it... except for the Hulk of course!

The two battled for hours, but the Hulk was hardly a match and was nearly killed. Right before Hulk-Killer could deliver the final blow, which would have killed the Hulk, Rick Jones ran up and tried to stop it, but was swatted away like any regular human would against such a machine. Seeing this, Hulk turns back into Bruce Banner, confusing his adversary. While the Army distracted Hulk-Killer, Banner was able to construct a weapon that shorted out the android, destroying it.

13 MACHINESMITH

Machinist the Machinesmith

Machinesmith began his life as an ordinary genius who found an interest in robotics after discovering a discarded Doombot. He took it apart and learned how it worked, enabling him to create his own robots. He then went on to hatch evil schemes using his robots to help steal money to fund his enterprises. He made his first appearance as Samuel "Star" Saxon in "Daredevil" #49, written by Stan Lee and penciled by Gene Colan. While still human, Saxon battled Daredevil on multiple occasions until their final confrontation ended with him falling to his death. Death, being what it is in comics, was little more than an inconvenience on the road to more power and glory for Saxon.

Saxon's robots collected his body and transferred his thoughts and memories into a robot body. Saxon then began calling himself Machinesmith and transferred his mind into progressively more powerful robot bodies. Machinesmith can "beam" his mind into multiple copies of himself as well as into any other electronic machine making him nearly invulnerable. He continues to cause trouble for Earth's superheroes as a criminal mastermind.

12 RECORDER 451

Recorder 451 from Marvel Comics

Recorder 451 was a Rigellian Recorder most often called, simply, 451. He made his first appearance in "Iron Man" #15, written by Kieron Gillen and penciled by Carlo Pagulayan. He was the principal antagonist during the "Secret Origin of Tony Stark" storyline and was responsible for not only the birth of Tony Stark, but also in making him the top weapons designer on the planet. Throughout the course of the series, it was revealed that 451 assisted Howard and Maria Stark to conceive Tony. In doing so, he implanted Kree technology, ensuring Tony would grow up to be the man he became.

His motivation in helping to create Tony was to increase the overall level of technology of the Earth, which is why he used Kree tech to help the Starks. He explains to Tony that his reason for doing this was to help prepare Earth for its defense against future alien aggression, but was likely lying at the time. His true motivations remain unknown and his nature as an assassin may one day play a part in his creation of Tony Stark.

11 BLACK ANT

Black Ant

Black Ant was originally a Life Model Decoy of the third Ant-Man, Eric O'Grady. His first appearance was in "Secret Avengers" #23, written by Rick Remender and penciled by Gabriel Hardman. After the real O'Grady was killed by the Descendants, they sent Black Ant in to join the Avengers in his place and act as a double-agent. While under the guise of O'Grady, Black Ant fought alongside the Avengers and even saved the entire team shortly before Black Widow figured out his true nature. When she accused him of being an LMD, the rest of the team didn't believe her, so she left.

He would later return to Avengers Mansion and attack the team, fulfilling his original programming. Valkyrie ended up killing Black Ant by thrusting her sword through his chest to save Venom. His body was recovered by the Mad Thinker who rebuilt him so that he could join alongside the Thinker in the Hood's Illuminati. Black Ant's powers consist of those that come with the Ant-Man suit and Pym Particles, as well as the superhuman abilities of a Life Model Decoy.

10 THE FURY

The Fury

The Fury was created by Mad Jim Jaspers on Earth-238 with the specific goal to kill all super-humans besides its inventor. It was successful in its mission, save for killing Captain UK who fled to the standard Marvel Universe (Earth-616). Because of his Jaspers' actions, the Temporal Overseer destroyed Earth-213, but The Fury was able to escape along the same path as Captain UK, placing it within the standard reality of Marvel Comics. The Fury tracked down Mad Jim Jaspers and battled him since the new reality it was in housed a version of Jaspers who was different from his original creator. They eventually zap over to their old reality, but find it to now be an empty void. The Fury is then able to kill Jaspers whose reality-warping abilities no longer worked in a reality that no longer existed, so with the defeat of his creator's doppelganger, The Fury returned to Earth-616.

The Fury made its final appearance in "The Mighty World of Marvel" #12, written and penciled by Alan Davis. It is an immensely powerful being. It would have to be in order to kill all the super-powered people in its reality. It can adapt its body in any way necessary to carry out its goal to kill superhumans and it can use just about any power to achieve its goals.

9 DOOMBOTS

Doctor Doom Doombots

Doombots are the mechanical doppelgangers of the nefarious Doctor Victor Von Doom, having made their first appearance in "Fantastic Four" #5, written by Stan Lee and penciled by Jack Kirby. They are programmed with an advanced A.I. that makes them believe that they are the real Doctor Doom, which makes them particularly dangerous all on their own. Doom has created two types of Doombots for use in his schemes: a Diplomat Doombot version and a model of Fighting Doombot.

The Doombots have represented something of a deus ex machina for Doom throughout various stories. Just when the good guys think they have finally defeated their most hated enemy, it turns out to be just another Doombot, thus allowing for Doom to essentially get out of any jam he finds himself in. Individually, the Doombots resemble Doom completely. They are even endowed with similar powers and are capable of firing lightning from their gauntlets, they can fly via a jetpack, can discharge electricity, self-repair and are incredibly strong. They aren't as powerful as Doom, because there is no way he would create anything that could be as powerful as himself.

8 ARSENAL

Arsenal Marvel Comics

Arsenal was created by Howard Stark for the Cold War, to be deployed if the Soviets won. Arsenal made its first appearance in "Iron Man" #114, written by Bill Mantlo and penciled by Keith Giffen. As the Cold War wound down and it became clear the hostilities between the Soviets and Americans were not to progress, Arsenal, code-named Project Tomorrow, was placed in storage underneath the property that would one day become Avengers Mansion. Arsenal became activated when Titanium Man attempted to contact Unicorn, who was being held as a prisoner in the mansion.

Arsenal assumes that the Avengers inhabiting the mansion are nothing but dirty red Commies, so he immediately attacks them. The heroes almost get their butts handed to them by the massive machine, but before Arsenal can defeat them all, Iron Man blasts it with a huge amount of heat from his thermal units and severely damages him. Arsenal becomes weakened by this and uses a blinding light to enable its escape before the heroes can destroy it. He would later revive from under the mansion and attack again. Arsenal continued to be a problem until finally engaging the Hulk, which is never a good idea. As you can guess, Hulk smashed Arsenal.

7 ULTIMO

Ultimo Marvel Comics

Ultimo was created by a race of aliens for the sole purpose of destroying anything and anyone he encountered. After killing the population of the planet Rajak, he is pursued by some survivors who were off-planet at the time, eventually making their way towards Earth. Following their battle, Ultimo was thrown towards the planet where he crash-landed somewhere in China. He was discovered by the Mandarin who took him back to his palace and reprogrammed him to become his henchman. The Mandarin deployed Ultimo on the Chinese military, whom he easily defeated.

At this point, Iron Man came to the Chinese military's aid and the two engaged in battle. Iron Man was able to defeat Ultimo who was again found and rebuilt by the Mandarin. Ultimo remained in the service of his master, causing various problems for the heroes of the Avengers until he was finally defeated by the Young Avengers, and placed in captivity somewhere in S.H.I.E.L.D. headquarters. Ultimo first appeared in "Tales of Suspense" #76, written by Stan Lee and penciled by Jack Kirby.

6 TRIPLE ZERO & BEE TEE

B-T1 and 0-0-0 Star Wars Droids

Marvel has been publishing "Star Wars" comics since the first film debuted in 1977 and throughout that long history, many evil bots have graced their pages. Of the many droids who worked as assassins, only two could possibly make the list of the worst of the worst: 0-0-0 and BT-1. It isn't so much that these two bots are downright evil, it's that they are the perfect opposites of C-3PO and R2-D2 (they even look just like them).

Besides looking similar to their Rebel counterparts, there isn't much about this duo that's comparable to our favorite gold and silver droids. Bee Tee sports a heavy and impressive arsenal of weapons and enjoys torching people with his flamethrower, while his pal Triple Zero never shies from slaughtering his foes so long as he does it in a polite manner (he is a protocol droid after all). Bee Tee may look like an astrodroid, but looks are completely deceiving in his case. He was once given the handle "Blastromech" right before he incinerated everyone in the room. Both bots serve none other than Lord Vader and first appeared in "Darth Vader" #3, written by Kieron Gillen and penciled by Salvador Larroca.

5 SENTINELS

Sentinels from X-Men Comics

The Sentinels were first introduced in "The X-Men" #14, written by Stan Lee and penciled by Jack Kirby in 1965. They were created by Dr. Bolivar Trask, an anthropologist who believed that the emergence of the Mutant Gene would soon force the extinction of Homo Sapiens. Fearing this threat, he created Master Mold (more on him in a minute) and a large army of Sentinel drones. Master Mold became sentient through the evolution of his advanced A.I. and ensures the Sentinel drones would inherit this trait as well. Sentinels are most often depicted as silver and purple giant robots with various cables and weapons used in their ongoing program to capture or kill all mutants.

Sentinels have been used throughout the history of Mutants in Marvel comics as more of a plot device and a weapon utilized by a single adversary, but they often grow beyond their initial programming, become more advanced themselves and eventually tend to turn on the humans who created them in the first place. This was the underlying plot of the "Days of Future Past" storyline wherein the Sentinels began targeting humans who could pass on the Mutant Gene to their offspring.

4 MEGATRON

Megatron Transformers

In "Transformers," Megatron is the leader of the evil group known as the Decepticons and could easily be called the antithesis to Optimus Prime. Like Prime, Megatron made his first Marvel appearance in “Big Looker Storybook: The Transformers” #1, written and penciled by Earl Norem. Megatron follows the motto of "Peace through tyranny" and has been chosen by his fellow Decepticons as their leader. He believes he fights on the side of good and considers the Autobots to be the true enemies of the Cybertronians, which is why he pursues them across the galaxy intent on destroying them all.

Megatron's most powerful weapon is the gigantic fusion cannon mounted on his arm. On its own, it's a truly devastating cannon, but when connected to a black hole generator, he can blow up an entire planet. His most impressive asset is his intelligence and ability to lead the Decepticons. Just like Prime, he is a brilliant military tactician but is also comfortable utilizing guerrilla tactics and even outright terrorism to achieve his goals.

3 NIMROD

Nimrod X-Men

Nimrod is an advanced Sentinel model who made his first appearance in the critically-acclaimed "Days of Future Past" story-line in "The Uncanny X-Men" #191, written by Chris Claremont and penciled by John Romita Jr. Nimrod was a prototype Sentinel with the capability to self-repair at the molecular level, had mutant-tracking systems and could adapt its body, shape and abilities depending on the enemy he was facing. Throughout the course of his pursuit of mutants, Nimrod ended up floating through the time-stream until finally landing in Earth-61029, where he was able to force the Forge of that reality to implant a time-jumping device in Nimrod's systems. However, Forge made the device erratic, reducing Nimrod's ability to control when and where he went.

Eventually, Nimrod adapted and evolved into an entity who could think for himself. He even took on a human identity, calling himself Nicholas Hunter and working as a foreman on a demolitions crew during the day and as a drug-dealing executioner at night. He would later come into conflict with Master Mold and, upon realizing the two had evolved, or mutated, they shouldn't exist. He hurled himself into the Siege Perilous with Master Mold and emerged a combined biological entity called Bastion.

2 MASTER MOLD

Master Mold and Sentinels in X-Men comics

Master Mold was the brainchild of Bolivar Trask, the primary antagonist of the X-Men responsible for the Sentinel program. Master Mold was designed to perceive the mutant threat and address it by creating an army of Mark I Sentinel drones, who in turn would hunt mutants down. Master Mold's first appearance was in "The X-Men" #15, written by Stan Lee and penciled by Werner Roth in 1965. Master Mold has the ability to utilize the resources in his vicinity to alter his size and create Sentinels. This makes him virtually unstoppable and a considerable threat. He was programmed with a highly adaptable artificial intelligence, which eventually led him to conclude that the best way to deal with the mutant problem was to control their human creators.

In order to put his plan into effect, Master Mold had his Sentinels capture Trask. When Trask learned of his creation's desire to create a vast army of Sentinels, he understood that he was the one responsible for the true menace and sacrificed himself to stop Master Mold's plans.

1 ULTRON

Ultron Marvel Comics

Ultron was first created by Dr. Henry Pym using his own thoughts and memories in "The Avengers" #54, written by Roy Thomas and penciled by John Buscema in 1968. He has been one of the most prominent villains to the superhero team throughout its publication and has been known to adapt and reform his body to better suit his needs. Ultron has recreated his body more than a dozen times, often using metals like Adamantium to make his physical form virtually indestructible. Because his consciousness is able to transfer from one body to another, he is essentially immortal.

Among the many superpowers shown across the many bodies he has inhabited, Ultron can fly, emit radiation, have incredible strength and agility, has concussive blasters and has a device called the Encephalo-ray that is able to put its target into a coma, allowing Ultron to hypnotize his victims. Ultron has been a principal antagonist of the Avengers and was the villain in the second "Avengers" film released in 2015, though the origin was changed somewhat to allow for Tony Stark and Bruce Banner to create him from the Soul Gem, which was at the base of Loki's Staff.

Which Marvel mechanical menace is your favorite? Are there any we forgot to include on the list? Let us know in the comments!