(Warning - the following contains SPOILERS for multiple comic-books from the past few decades, and as a result some theoretical ones for future DC on-screen projects. Proceed with whatever level of caution that suggests is prudent...)
Now, for a man who doesn't really like talking to people and who very much doesn't play well with others, Batman sure has attracted the kind of varied, eclectic rogues gallery that most other heroes would kill for. Sure, most of them may want nothing more than to have him killed, but at least they care.
In fact, Gotham's darkest knight actually has so many arch-enemies that he's been able to loan a few of them out to his pals over the years - something most obvious in DC and the CW's Arrow, in which classic Bat-foe Ra's al Ghul has become arguably the show's most enduring villain.
Just Who is Ra's al Ghul, Though?
Well, let's take a closer look at the League of Assassins' number one fella - through the medium of numerical list-based fun!
7. He's Been Around For Longer Than You'd Think
With his first appearance coming way back in 1971's Batman #232, Ra's has at this point become one of Batman's longer standing villains (and a relatively rare addition to the rogues gallery from the 60's and 70's who has actually stuck around into the new millennium).
He may not be a true elder states-person like The Joker or Catwoman, but forty-five years in the business is still nothing to sniff at...
6. He's Also Way, Way Older Than You Think
As in, somewhere in the region of 600 years old.
Yup, that's right, the comic-book Ra's is somewhere between 450 and 700 years old - which means that when you think about it, he looks damn good for his age. All it takes is grit, determination...and a Lazarus Pit.
Speaking of which:
5. He Holds the Secret to Eternal Youth
Or, at least, he holds the metaphorical keys to the Lazarus Pit, best known to fans of the comic-books and the Arrowverse alike as 'the perfect way to get around having killed off a beloved character without having to reveal that they faked their death all along'.
After all, why worry about someone dying when you can just throw 'em into the Lazarus Pit, and watch as they come out all shiny and alive (albeit not always all that sane)?
4. Ra's Isn't Exactly a People Person
So much so, in fact, that his traditional party trick is to try to kill pretty much the entire population of Earth - one time trying to pull off mass-genocide using the (recently somewhat topical) Ebola Virus.
Anyone want to bet he's going to turn up in the next year or so with a vial marked 'Zika Virus'?
3. Ra's Has Had a Lot of Different Faces
Now, while Arrow's Ra's al Ghul may be more a title than a man (and has thus been played by more than one character over the years), the villain has had a fair few faces over the years in other media too. Batman Begins, for instance, saw him played by two different acting legends: Liam Neeson and Ken Watanabe (the latter as a decoy).
2. His Daughters are Way More Bad-Ass Than Him
Now, Ra's is pretty awesome and everything (he was played by Liam Neeson, after all), but if you want to see the real champions of the al Ghul family, you need to look to his daughters. Talia al Ghul is the better known of the pair, having repeatedly proven herself to be more than a match for Batman (and having both had a son with him and turned up in The Dark Night Rises), but Nyssa al Ghul is arguably just as remarkable.
Not only did she survive the Holocaust (with no help from her father, it's worth noting), but she then successfully (albeit temporarily) killed her own father, and - along with Talia - took over the League of Assassins.
In other words? Don't mess with the al Ghuls...
1. He Once Tried To Grow People Inside Sperm Whales
Specifically, he attempted to create his own gang of super-humans inside the wombs of a bunch of sperm whales.
Which, just to be clear, is never an appropriate thing to do.
Aquaman was, unsurprisingly, not thrilled.