A quarter-century after “Batman” ushered in the era of Hollywood mega-tentpoles — hollow comicbook pictures manufactured to enthrall teens and hustle merch — a penitent Michael Keaton returns with the comeback of the century, “Birdman or (The Unexpected Virtue of Ignorance),” a blisteringly hot-blooded, defiantly anti-formulaic look at a has-been movie star’s attempts to resuscitate his career by mounting a vanity project on Broadway. In a year overloaded with self-aware showbiz satires, Alejandro G. Inarritu’s fifth and best feature provides the delirious coup de grace — a triumph on every creative level, from casting to execution, that will electrify the industry, captivate arthouse and megaplex crowds alike, send awards pundits into orbit and give fresh wings to Keaton’s career.

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Keaton was a controversial choice to play the Caped Crusader back in 1989, though the role was the best and worst thing that could have happened to the “Mr. Mom” star, who became world-renowned but never found another role of that stature — and who didn’t get nearly the same boost from working with Tarantino (on “Jackie Brown”) that John Travolta and Bruce Willis did (from “Pulp Fiction”). As Riggan Thomson, Keaton isn’t playing himself so much as an archetype that few other actors could have fit: an insecure celebrity whose Faustian decision to embody a superhero called Birdman subsequently made it impossible for critics or audiences to take him seriously in anything else. Riggan is one of those roles, like Norma Desmond in “Sunset Blvd.,” that relies heavily on the actor’s offscreen persona, and it works because audiences know so little about Keaton’s private life, though they find him endearing even when he’s playing narcissistic characters.

It’s hardly the first time the movies have cannibalized themselves for subject matter, and yet, Riggan’s dilemma seems larger than that of one actor. His crisis is somehow universal, possibly even cosmic, as suggested by the apocalyptic sight of a dying star flaming comet-like across the screen at the outset of the picture. Cut to Riggan, levitating calmly in his dressing room the day before previews begin for his big play. It will be more than half an hour before the next obvious splice — a trick that d.p. Emmanuel Lubezki learned on “Children of Men,” and here he extends the illusion of long, uninterrupted takes for nearly the duration of the entire feature as the behind-the-scenes tension escalates through to opening night.

For his Broadway debut, Riggan has selected Raymond Carver’s “What We Talk About When We Talk About Love,” adapting the short story in such a way as to give himself all the glory, from the bathetic monologue that comes just before intermission, to the ballistic finale (invented for the play), which sees his character blowing his brains out moments before the curtain falls. This is a movie-star approach to theater, where truly great stage actors let their co-stars shine. But then, Riggan has something to prove, surrounding himself with pros — including a respected old friend (Naomi Watts) and the much younger actress he happens to be shagging (Andrea Riseborough) — in hopes that they make him look better. And when an accident allows Riggan to replace a weak player with someone better, Mike (Edward Norton), he leaps at the chance, clearly unprepared for what sharing the spotlight with a real actor entails.

If agreeing to play Birdman represented some sort of artistic sellout earlier in Riggan’s career (a compromise compounded when he agreed to make two sequels), then this Carver play ought to earn back his cred. Or so he figures, surrounding himself with a yes-man producer (Zach Galifianakis, in masterfully subtle control of his comedic impulses, except for one moment, where he inexplicably mispronounces “Martin Scorsees”) and other sycophants. Riggan has even gone so far as to convince himself that he has telekinetic powers, using his mind to move objects and taking advice from the disembodied voice of Birdman (Keaton’s own, lowered a register). But his druggie daughter/assistant, Sam (Emma Stone), calls his bluff, eviscerating his irrelevance in a rant sure to win over a generation too young to have seen Tim Burton’s “Batman.”

This is perhaps one of the unexpected virtues of ignorance referred to by the film’s evocative full title: Riggan approaches the Carver play without all the baggage of a traditional Broadway actor, but then, theatergoers approach it with different expectations as well, ranging from the spiteful prejudgment of a jaded New York Times critic (Lindsay Duncan, trying to seem her Meryl Streepiest) to the naivete of youth. (Oh, to pluck out Sam’s eyes and see Broadway through them!) The film virtually overflows with references, to contemporary blips such as Justin Bieber and established minds like Roland Barthes, managing to be simultaneously crude and urbane, while speaking to different audiences on whatever intellectual level they prefer.

As for intent, Inarritu and co-writers Nicolas Giacobone, Alexander Dinelaris, Jr., Armando Bo are clearly taking a generational stand with this script, which mourns a time when Hollywood actors had the chance to play flawed and fascinating men, as opposed to one-dimensional supermen. Like last year’s “The Great Beauty,” “Birdman” finds itself parsing a deep creative and existential crisis, never allowing its justifiable cynicism to drown out what idealism remains, even as it observes that our finest screen actors — Michael Fassbender, Robert Downey Jr. and Jeremy Renner among them — are all cashing comicbook paychecks these days (even as it conveniently pretends that Norton’s “Hulk” never happened).

Norton very nearly steals the show from Keaton at one point. Revealing body and soul alike, both stars are inviting us to laugh at aspects of their real selves, though Norton initially seems the more impressive actor, amplifying his own intense commitment to realism to absurd extremes — with the hilarious result that finding himself in the moment during an early performance proves a rather dramatic cure for his character’s offstage impotence. At first, Keaton doesn’t seem capable of reaching as deep, either in reality or as Riggan, though that’s before the humiliation of wandering through Times Square crowds nearly naked.

“Birdman” offers by far the most fascinating meta-deconstruction of an actor’s ego since “Being John Malkovich,” and one that leaves no room for vanity. From the moment Keaton first removes his wig to the sight of him wrapped in Batman-like facial bandages, his performance reveals itself in layers. The role demands that he appear superficial and stiff onstage, while behaving anything but as the character’s personal troubles mount and his priorities begin to align — at which point, he appears in a dual role, donning the ridiculous Birdman costume to hover, seen only by Riggan, like a cracked-out version of Broadway’s own “Harvey.”

Judged by Howard Hawks’ quality standard — “three great scenes, no bad ones” — “Birdman” features at least a dozen of the year’s most electrifying onscreen moments (scrambled, so as to avoid spoilers): the levitation, the hallucination, the accident, the fitting, the daughter, the critic, the ex-wife, the erection, the kiss, the shot, the end and Times Square. Most films would be lucky to have one scene as indelible as any of these, and frankly, it’s a thrill to see Inarritu back from whatever dark, dreary place begat “21 Grams,” “Babel” and “Biutiful,” three phony, contrived melodramas engineered to manipulate, while posing as gritty commentaries on the harsh world we inhabit.

With “Birdman,” the director has broken from his rut of relying on shaky handheld camerawork to suggest “realism,” or an invasive Gustavo Santaolalla score to force the desired reactions, instead finding fresh ways to delve into the human condition. (He has even altered his onscreen credit, condensing “Gonzalez” to a mere “G.,” as if to acknowledge this new chapter.) Yes, the film is preoccupied with an aging actor’s psyche, but it also addresses fatherhood, marriage, personal integrity and the enduring question of the legacy we leave behind — as in an amusing scene in which Riggan imagines being upstaged by “Batman and Robin” star George Clooney in his obituary. Above all, it is an extremely clever adaptation of Carver’s short story, simultaneously postmodern (ironically, a rather retro label) in its meta self-parody and cutting-edge, owing to the dynamism of its style.

Circling shark-like around Keaton, then darting off to stalk other actors, Lubezki’s camera is alert and engaged at all times, an active participant in the nervous backstage drama. Taking a cue from Alfred Hitchcock’s “Rope,” the meticulously blocked shoot cleverly finds ways to mask cuts, using invisible visual effects to stitch together various scenes so it appears that the entire film is one continuous take, even though the events take place over several weeks and in various midtown Gotham locations — primarily Broadway’s St. James Theater, but venturing out anywhere that Riggan can walk or Birdman can fly.

In addition to being a virtuoso stunt in its own right, this single-shot illusion serves to address the critique that screen acting is somehow less demanding than stage acting, since there are no conventional editing tricks in place to shape the performances. The cast has no choice but to ante up, which everyone does in spades, and the film is built generously enough that everyone gets ample time to impress (although it should be noted that none of the background sexual intrigues amount to anything).

Inarritu’s approach is mind-boggling in its complexity, nearly as demanding on Lubezki as “Gravity” must have been, such that even seemingly minor jokes, as when the camera spies the drummer responsible for the pic’s restless jazz score (by Antonio Sanchez) lurking on the edge of the frame, had to be perfectly timed. It’s all one big magic trick, one designed to remind how much actors give to their art even as it disguises the layers of work that go into it.