With the rise of Comic Book movies, film studios are granted access to an immense library of characters. More often than not, directors and screenwriters take the elements of some of these characters and implement them into another for their vision. Here are five examples that, intentionally or not, combined two characters into a single one for their cinematic debut.

5. Batman Returns: The Penguin + Killer Croc

© DC Comics/ Warner Bros

The Penguin is the odd egg (no pun intended...okay, maybe a little) in the Batman rogue's gallery. He is closer to the mob-boss type villain, having his hand in more real-life crimes like gambling, prostitution, and drug running, avoiding the archetype of the wacky madman with a theme (though Oswald Cobblepot does love himself some birds) while maintaining the facade of legitimate businessman with aspirations to high society.

Director Tim Burton, however, went another route for his film “Batman Returns” and made the Penguin a physically deformed sewer dweller and former circus freak show act. While at first glance the change seems to have been made so to fit in Burton's frequently used storyline of the disfigured outcast who can never fit in (quote: “You're just jealous, because I'm a genuine freak and you have to wear a mask!”), this version seems to have incorporated elements of another Bat-villain: Killer Croc.

While some parts that are associated with Croc (sewer dwelling, animalistic attributes, cannibalism) came later in the character's life, he's always been a social outcast due to his deformities.

The Burton Penguin exhibits the same traits that both characters share, that of a deformed man who yearns to be part of normal society, despite clearly never being able to fit in, combining their most extreme elements into one disturbing creature that both hates and longs to be part of the above world (like some grotesque little mermaid parody made by that angsty teen you knew back in high school).

4. Batman Begins: Ra's al Ghul + Henri Ducard

© DC Comics/ Warner Bros

In the original comics, Henri Ducard was one of the many teachers that young Bruce Wayne studied under during his training to become the world's greatest detective, only later to be revealed to be a mercenary. While not evil per se, he was clearly someone whose methods did not agree with Batman's sense of justice. Ra's al Ghul, on the other hand, is a terrorist who thinks that to save the world, he must cull the population through acts of mass murder. While Ra's is a great villain on his own, he doesn't share much of a personal connection with Batman before meeting him (outside of wanting the Dark Knight to produce him an heir). This was changed when the character was adapted for the screen.

In " Batman Begins", Ducard plays the same role, albeit as a member of the League of Shadows under Ra's al Ghul, who seek to destroy Gotham city in their way of bringing global balance, only to reveal [SPOILERS] that Ducard was, in fact, Ra's al Ghul all along (though the beard was a tip-off, as well as the wasted Ken Watanabe performance).

The film combines both of the relationships Bruce Wayne had with these characters in the source material, with the fallen mentor angle from Ducard, mixed with the terrorist that is Ra's al Ghul, allowing more of a personal conflict when Batman is forced to go up against the man who trained him, who is also a mass murderer that has no qualms with the terrible methods he uses.

3. Dr Strange: Baron Mordo + The Silver Dagger

© Marvel Entertainment

In 2016's “Doctor Strange”, the eponymous doctor strikes up a friendship with a fellow student of the Ancient One, Karl Mordo, played by Chiwetel Ejiofor. Towards the end of the film [AGAIN, SPOILERS], Mordo becomes disillusioned by the acts and abilities of his fellow magicians and is hinted at becoming a sort of witch-hunter, going after those who he deems use their magic skills recklessly.

In the comics, however, Mordo is the more typical fallen apprentice, a student of the Ancient One whose lust for power leads him down the road of darkness. The film version of Mordo has more in common with a more obscure Dr. Strange villain; the Silver Dagger.

The Silver Dagger, a former cardinal, became a witch hunter when he became overwhelmed with the perceived evils of the world, to the point of actually murdering Dr. Strange and trapping his soul inside the Orb of Agamotto (Strange got better, of course).

In many ways, the Silver Dagger is the exact opposite of Dr. Strange. He hates the mystic arts and sees them as a threat to the world rather than a tool to save it. This is implemented in the film version of Mordo, who in the comics was more of a typical power-hungry rival to Strange, but is now changed to a man whose belief is shattered when the Ancient One (Tilda Swinton) is revealed to have drawn power from the evil Dormammu, causing him to hunt other magic users. Combining this arc of the fallen friend with the vengeful fanatic makes Mordo a unique villain in the MCU, which it sorely needs.

2. Iron Man 2: Crimson Dynamo + Whiplash

© Marvel Entertainment

While arguably a very flawed and unfocused film, the main themes in “Iron Man 2” of political unrest brought on by the rise of technology harkens back to the comic's Cold War roots. In the early days of the comic, many of Tony Starks enemies were either communists, spies or traitors, drenched in the environment of the then-current arms race between the US and the Soviet Union. This, of course, needed to be updated when Marvel adapted the character of Ivan Vanko, the Crimson Dynamo, since the lack of a Soviet Union kind of killed that once-popular hook.

Now, Vanko is stirred by personal revenge against Tony Stark, wielding a pair of supercharged whips to evoke classic Iron Man villain Whiplash, a goofy themed villain with a thing for whips. But this wasn't just a case of a name being given to a different character. In the film's climax, Vanko dons the Crimson Dynamo battle suit, now equipped with its own pair of whips, acknowledging the merging of the characters.

The reason behind this merger makes sense in context. Vanko, while a genius, is practically penniless at the start of the film, so him having a Crimson Dynamo suit from the start would be strange. The use of the whips, that he could make from scrap material, allows Vanko to show off his knowledge and inventor skills at a low-budget scale, while at the same time allowing the film to throw a nod to a character that would have otherwise never seen the light of day in the MCU.

1. X-Men: Days of Future Past: The Sentinels + The Fury

© Marvel Entertainment/ FOX Entertainment

The 5th official X-Men film adapts parts of the classic “Days of Future Past” storyline, where the X-Men receive a troubling message of a dark future where mutants and humans are imprisoned, hunted and killed by the murder machines known as the Sentinels. The same happens in the film, but the machines in question seem to embody a character from a different but similar storyline from another Marvel book.

In the comics, and the versions that appear in the parts of the film that take place in the 70's, the Sentinels are large robots covered with a lot of purples (so, so much purple). However, the versions of the killer robots seen in the future scenes more closely resemble another hero-killer from the British Marvel magazines, The Fury. Created by Alan Moore and Alan Davis during their run on "Captain Britain", The Fury was a bio-mechanical assassin (or Cyboid) that could adapt itself to kill any super powered target, even obliterating the powerful Captain Britain in a single shot (he too, got better). Acting more like a slasher-horror monster than a super-villain, the Fury comes for its target, never letting up until they are dead, indifferent to who gets killed in the crossfire.

The film version of the Sentinels adds not only the sleek black and yellow look, but also the horror elements of the Fury, the silent brutality, and efficiency of they way it kills, with the frightful image of the heroes being overwhelmed by sheer number, marked for death by their own genetic make-up, that come with the Sentinels. A nice combination of Marvel's two greatest killer robots that aren't Ultron.