Without a doubt the most famous villain of the DC Comic Book Universe, and arguably the most interesting and most well-known villain of all time, Joker has been around since the first issue of Batman hit the stands. For 76 years (well, almost), he has accompanied the Dark Knight like a shadow, effectively making him what he is today: the hero who has to deal with the most dangerous specimen to come out of a writer's mind.

That has to say something, given the fact that the Joker possesses no superpowers (most of the time, of course).

It’s understandable that some people might have forgotten some small – but very interesting – details from this character's history. And it’s understandable, because his past has been kept pretty vague thus far, even if some origin stories exist. Most recently, Christopher Nolan decided to keep the Joker's past hidden - and this made Heath Ledger's Clown Prince of Crime even more terrifying.

So, what if we dig a little deeper in the 70-something-year history of the character? What will we find in there? That’s what this list is all about: The ten most interesting details from the Joker's past (we can bet we'll find some skeletons buried in here, somewhere).

The sanest of all comic book characters

When most people think about the Joker, they think about the insane serial killer who goes on murderous rampages just because. However, is he really insane? All evidence seems to suggest the contrary, especially with his rather complicated plans to incapacitate the Batman. Can an insane person keep track of all the moving parts of an intricate plan? We guess not.

Maybe he is hiding in plain sight, we say, and maybe his insanity is just a façade. Maybe he is fed up with seeing everything as it is, and that is why he goes on killing as many people as he kills.

And we don't say that without backing our words. Grant Morrison even said that Joker is sane. Better yet, an easier explanation comes from Christopher Nolan - his Joker simply states that he is ahead of the curve. Which means that he has outgrown the human condition towards something else.

Basically, the Joker (in all of the iterations to date) feels no moral restraint. And this isn't the same with saying that he doesn't know what good and evil are - these are just hollow concepts of no interest to him. Introducing the super-sanity is DC's way of saying that the Joker knows he is in a comic book, that he sees all the strings.

Sanity is a fitting explanation for how the Ace of Knaves has escaped, and even beaten, the Dark Knight so many times.

The Ace of Knaves

Speaking of this alter-ego, there must be a way to find out where it all began. So the most widespread legend is that Bill Finger, Bob Kane, and Jerry Robinson (the character’s creators) based his appearance on actor Conrad Veidt from The Man Who Laughs. But, as emphasized, this is just a legend. And the truth is that the Joker has no (certain) origin.

In other words, the creators of the character cannot agree on a point of origin. Bill Finger said that it all began with the aforementioned actor. Bob Kane says that the character was born after seeing a simple playing card. Lastly, Jerry Robinson says that he just drew a character which happened to resemble Conrad Veidt.

We guess that the truth is out there somewhere, known only to the Joker himself.

Speaking of starting points, we must also add that the most agreed upon story is that the Joker used to be an enforcer called Jack Napier (just like the Jack Nicholson version from Tim Burton's Batman). And this is interesting, since Jack Napier is just a pun itself, a word-play for jackanapes (a smart-mouthed, dishonest person).

To make it even more interesting, the Ace of Knaves (which is a nickname for the character) is also the title of a collection of mystery novels featuring Simon Templar, aka The Saint. And, if you didn't know, the first time The Saint appeared in Leslie Charteris' writings he was called the Joker. Go figure.

But we guess the Joker would like that. After all, he did say that the question regarding his beginnings shouldn’t have just one answer.

He used to be a rather tame guy

Back when the Jester of Genocide appeared, he was a rather tame guy - it was required for him to be so since, well, those were different times. Yes, he was obviously a criminal - but so was Batman, who wasn't too shy when it came to killing the villains, and with the gun that killed his parents.

So, besides his first appearance, when he was actually trigger-happy, the Joker was more of a pest than a murderous psychopath (we know he is sane, but the comic book characters with whom he interacts say that he is a lunatic). Robbing banks, getting caught, eventually escaping, robbing banks, getting caught, and so on - it’s a never-ending circle. Censorship was prevalent back then, so the comic books couldn't contain any sex, harsh language, or gruesome murders.

A pest, a nuisance who couldn't hold a candle when compared to today’s version.

But something from that age stuck with him - the use of gimmicks and goofy-looking gears. And from the first edition in which he appeared, there has been the use of Joker toxin. At least we are certain of that"¦

He disappeared for almost a decade

As previously mentioned, in the beginning, the Joker was something like an average villain. Which was no good because, after all, you don't actually need someone like the Dark Knight to catch a simple prankster. Furthermore, by using him, the writers needed to dumb down the awesomeness of the Batman - which meant that, slowly, the Joker became less and less prominent in the comic books.

Thus, for the better part of the "˜60s and the first part of the "˜70s, the murderous clown was almost nowhere to be seen. Batman had to deal with other kinds of criminals, such as the Penguin.

It seems almost impossible for the yang to miss the yin. It seems almost impossible for the Dark Knight to function without the Joker, the one who tested him and proved that he was a hero. But it happened.

That was until '73, four years into the total disappearance of the character. Then, in an attempt to boost comic sales, DC went back to its roots and reintroduced the Joker as the murdering psychopath who kills people, just because. The Joker's Five Way Revenge was the storyline that brought him back and showed that he works better when he is used as a central character of overarching stories.

The imperfect beginning

There was a time when a comic book villain appeared in just a single issue. Those were the "˜40s, back when the Joker first appeared. Those were the times when the Dark Knight was dark indeed, acting as judge, jury, and executioner. The "˜40s were the decade when Batman simply capped a fool and then ran away from the crime scene.

Such was the case of the Clown Prince of Crime, who made an entrance into the comic book world by using his signature toxin. Because the writers believed that a returning villain would make Batman boring, they decided that the best way to end the story was to have the enemy stabbed in the heart.

No, Batman wasn’t the one to do it - it was all just an accident (although the Dark Knight was still supposed to run away from the police, as if he did it). That was the way a hero dealt with a villain.

Fortunately, we were spared from that fate of going through life without having the Jester of Genocide in our comic books. Whitney Ellsworth (who at that time was the chief editor with DC) decided that this was too interesting a character to die. So the final page didn't show the Joker dying - the readers were supposed to believe that he met his end, only to be surprised in the next issue that he survived the accident.

Close call, DC! Very close!

The Jester of Genocide

And then, after the great comeback, everything changed and the Joker that we all know was born (or born again), with more and more intricate plans to take out the Batman. For him, stepping on the Dark Knight’s toes is an art - and the art is killing!

The Jester of Genocide isn't essentially set on ruling Gotham, or the Earth, or the Universe. Killing is just a pastime for him and he doesn't shy away from doing even the most atrocious of all things (at one time he let a room full of babies die after killing the woman caring for them, and another time he ate the entire population of China). Of course, these are atrocious acts to everyone else, but not to him.

His mind and his reasons are so hard to guess at that even the most fearful villains stay out of his way - as Emperor Joker, he gleefully killed and resurrected Lex Luthor, over and over again. The word is that when villains want to scare each other they tell Joker stories.

Just call him the Joker

Throughout the years, the character has evolved, literally in all directions. He was both an enforcer, as well as an immortal. He was a regular man (as regular as such a character can get) as well as a nigh-omnipotent being. But even if any of those things changed, he was always the same.

Even when he was cured of his condition, you could have still recognized him, because of his hair, because of his smile, or because of his clothing preferences.

For this reason, the character cannot be impersonated by any other DC villain. Just like there is only one Batman, in the same way there is only one Joker - both of their names begin with The, and both of them are highly recognizable, no matter what aliases they use.

Super-sanity comes with super-intelligence

Batman is well-known for being one of the most skilled tacticians of the DC comic book universe. He is so famous for having contingency plans for all situations, that he is able to defeat anybody, even if he is not taking part in the battle.

So how can the Clown Prince of Crime escape him? Why doesn't Batman build a safe prison where the Ace of Knaves can rot?

It is simple - the Joker is also one of the smartest characters of all time (and here are the smartest superheroes). We've mentioned the Emperor Joker - although that story wasn't set in the canon universe, we can say that the Clown Prince of Crime became almost omnipotent because he tricked Mister Mxyzptlk into donating almost all of his power to him.

He is so smart that, at one time, he used his toxin gas to control the entire Justice League. Batman had to use all of his skills and assets to escape and catch the villain. As you can guess, he once again escaped. Which brings us to another point in the list.

A confusing relationship

We get it - Batman doesn't want to break his one rule and commit murder. But shouldn't he make an exception for the Joker? After all, in canon, Robin died a gruesome death at his hands - that surely has to count for something. By not killing him, Batman is in a way the accomplice of the Joker.

On the other hand, the Joker tried to kill the Batman. It seems that this is his purpose in life - to bring the other to the limits of his sanity and power, to push him until he collapses. And the Jester of Genocide actually managed to kill his nemesis.

Afterwards, everything changed - as if he had no purpose in life any longer, he became a normal person, having plastic surgery and living as a butcher or in some other normal job. Batman wasn't dead, though - and when he reappeared, so did the Joker. So why did that happen? Could it be because every hero needs a worthy opponent? It certainly seems so.

This is a very, very weird relationship, which can be explained by the Joker himself, who at one time (in Endgame) said that he is actually helping the Dark Knight improve himself, that he is actually very altruistic in his criminal endeavors. That is twisted, right?

An epic sidekick

Everybody knows Harley Quinn as being Joker’s sidekick. But it wasn't always so - she actually appeared quite late in his life, in 1992’s Batman: The Animated Series. So was there someone else before her?

In the "˜60s, the writers found the perfect answer; if Batman had a Robin, the Joker needed to have an equally skilled companion. And that was Gaggy Gagsworthy, a little person who walked the tightrope at the circus. However, when the flying Graysons arrived, he was sent to be a clown - he resented that and, at one point, he even lashed out at some of his fellow clowns.

Joker spotted him and took him under his wing.

Gaggy Gagsworthy didn't appear in too many issues. However, he misses the old Joker. According to him, Harley transformed the fun Clown Prince of Crime into a murdering psychopath.