The casting of Heath Ledger as the Joker in The Dark Knight has become the cure-all response to any outcries of disappointment about the casting of any major pop cultural characters in any major film, ever. (Heck, it nearly even worked on Batffleck.) Citing Heath Ledger's Joker as the ne plus ultra of out-of-the-box casting decisions works because that casting decision, itself, was based on such unassailably good reasoning.
When he cast Ledger as the Joker, Christopher Nolan was seeing ahead of Ledger's development curve as a movie star, instead of behind it. He was also seeing the foundation of accomplished physicality that underlay even Ledger's least interesting roles, which would pipeline directly into Nolan's intent for the character in The Dark Knight. The director correctly anticipated a perfect storm, that day in 2007 (albeit one with one more, wholly unpredicted and horrible, final movement). The result will loom over the genre filmmaking landscape for decades.
The great legacy of the Joker effect is that it provides solid ammunition for filmmakers and creative talent to hire established character actors, not movie stars, to play high-profile genre roles. It also provides incentive for those actors to take those roles. I'm sure there are a lot of actors in Hollywood who think, or want to think, they have a Joker in them: a performance interpretation so wildly original that it will help to define the genre.
This sort of thinking, on the part of both the actors and the directors, explains a whole lot of casting we've seen in the superhero space over the course of the six years since The Dark Knight. It explains (boo!) Mickey Rourke in Iron Man 2 and (yay!) Ben Kingsley in Iron Man 3.
It explains why you end up with a guy who is maybe the best actor alive, Michael Shannon, duking it out in a CGI super-suit in a movie that has no idea how to use him, while Shannon does his goddamndest to figure out a way through the madness. This is not, by any means, a perfect system.
When the Joker effect is working properly, you get brilliant blue-ocean casting strategy, actual star-making turns, like Tom Hiddleston's Loki in Thor - an instance where a genre director actually had the wherewithal to put a genuine unknown in the lead villain role of a major franchise picture, just because the actor was actually that good.
An interesting, but somewhat more worrying, side effect of the Joker effect is the other side of the coin: the design of the characters themselves. Ledger's Joker is not an incarnation of the character from the comic, in any form (although the comic incarnation has, of course, deftly shuffled in Ledger's direction since then). Like most of Nolan's bat-characters, Ledger's Joker is more of a real-world fever dream you might have if you glimpsed portions of the Joker's iconography without context, and then let your subconscious try to put the pieces together under the influence of Nyquil.
As a character design, it was an entirely canny move for The Dark Knight - creating a version of the Joker that fit the Chicago-Gotham landscape perfectly, while still being, if anything, scarier than the guy in the comic book - but it's important to remember that it was not a "faithful" adaptation in any way we can use the term.
Performances such as these are built more around the process of gaining a "take" on the character that can be articulated in the context of the film you're making, rather than remaining slavish to a perception of the importance of the source material, and I'm fine with it. When you don't do it, you get Christopher Eccleston as whatsisface in Thor: The Dark World, as unmemorable a comic book character on the big screen as I can recall in the decade-plus since Spider-Man.
Which, of course, brings me around to Jesse Eisenberg's casting, last week, as Lex Luthor in the Man of Steel sequel. As with any of the decisions made on the first Man of Steel film, if we are to remove from the equation the fact that Zack Snyder is incompetent*, the casting of the guy who played the guy from Facebook as the supervillain who defines the word has the faint whiff of against-the-grain genius about it.
I like Eisenberg a whole lot, and his casting in Batman vs. Superman is the first thing about the project that seems genuinely inspired. This ain't by any means the Luthor I grew up with, which is good: the Luthor I grew up with would (at best) be stale on the big screen, or (at worst) an outright failure.
I like that Eisenberg's casting veritably screams of the actor and the filmmakers having a "take" on Luthor that is far more evolved and conceptually original than the early stumping from the fanbase to have Bryan Cranston transplant his Heisenberg performance wholesale into Batman vs. Superman.
But I do hope the temptation to simply cast against type, and then run with it, is not becoming the governing factor in decisions like this. To return to the Ben Kingsley example above (spoilers!), once you have Trevor Slattery, the toast of Croydon, shucking the Mandarin robes to take the piss (well, in his case, the shit) out of the whole concept of supervillains, the game is kind of over on iconoclasm for iconoclasm's sake.
Repeating past successes ad nauseum is an unsustainable strategy; the reason casting Ledger worked so well in the first place was that it was smart, not rote. I can't see Eisenberg troubling Metropolis while dressed in a glowing Kryptonite super-suit, and hopefully, I'm not meant to. Casting against type for its own sake just shows how little you understand the world you're building. But here's hoping.
*unfortunately, we cannot remove Zack Snyder from this, or any, equation.
Destroy All Monsters is a weekly column on Hollywood and pop culture. Matt Brown is in Toronto and on Twitter.