WHY, is that a dagger we see before us?

Indeed, and one forged by the actor Richard Dreyfuss. Looking closer, we can see his engraving reads: “You read for a part, you feel good about it, you feel confident, then they cast Ben Affleck.”

Zing. By the ghost of “Gigli,” that stings.

Warner Bros. announced shortly before 9:30 p.m. Thursday that Ben Affleck is our new big-screen Batman. Within minutes, Dreyfuss — true to his brash and passionate (and yet still self-deprecating) style as an Oscar-winning actor — tweeted his artful thrust-and-parry, drawing first blood as the Internet responded to the casting fury that rapidly went by the handy hashtag #Batfleck.

And at that, the marauding online hordes arrived, bellowing like Bane. Surely the power of the Web could reverse the decision to put Affleck in the cape and cowl for the “Man of Steel” sequel, set for 2015. A change.org petition was launched that seeks to “Remove Ben Affleck as Batman/Bruce Wayne in the new Superman/Batman Movie” (Tens of thousands of signatures and counting.) And the Twitter hashtag #BetterBatmanThanBenAffleck spawned a gleeful piling-on (prompting answers as varied as TV original Adam West, the Dowager Countess of Grantham, the Autopilot from “Airplane” and “literally, anyone”).

Ben Affleck with one of his favorite sidekicks. (./Evan Agostini/Invision/AP)

But listen to me on this, Ben: It’s not you. (Well, it’s sort of you, after your spectacular acting nadir a decade ago, as you churned out flicks like “Gigli” and “Surviving Christmas” Marvel’s “Daredevil” like some reverse Olivier.) But now, mostly, it’s us.

Working with Warner Bros. — not coincidentally the same studio that shepherds the DC Comics universe — Affleck (after revivifing his descending-into-punchline career by directing “Gone Baby Gone” and “The Town”) capped his comeback this year, when he and his beard won the best-picture Oscar for “Argo.” Respect was again his.

Unless, you know, he actually tried to act again — especially when not directing himself.

The fickle Internet fumbled for reasons to justify its instinctual revulsion to the casting (sounding a lot like a meta-soliloquy by Affleck in the film “Jay and Silent Bob Strike Back”). Affleck is too strapping, they kvetched, or too square-jawed, or too famous — or too bland and too unsubtle and too deliberate and too smug.

All qualities, in other words, so often associated with Batman.

Ironically, Affleck made a deft professional comeback buoyed by his Golden Globe-nominated role in 2006’s “Hollywoodland,” in which he played “TV’s Superman,” George Reeves — another actor once accused on being too wooden.

(And for the record, Batman casting has a long and rich history of sparking public sniping, including one of the best big-screen crimefighters ever, Michael Keaton, and all the way back to Lewis Wilson, who was mocked in the role for his strong Boston accent — so perhaps there’s a twisted #BenAfflecksRevenge in this.)

Thing is, in another DC production from the intelligent and proven “Dark Knight” team, including writer David Goyer, Affleck will likely be fine. But the Internet doesn’t want “fine.” Or safe, unless “safe” means the high-priced return of Bale. Fanboys and filmgoers want either established brilliance — Daniel Day-Lewis or Daniel Craig, say — or at least a pick with an air of risk or creativity, like drafting someone from “The Walking Dead.”

The Internet wants much the same thing from its major-role casting, in other words, that it wants from its very superhero films: Daring. Boldness and bravado. Thrills. Perhaps an element of surprise.

And if you could manage it, Warner Bros., something please approaching perfection.

Have your people tweet our people. We’ll work something out.