So many truths only become clear with hindsight. Here's one of them: Unbeknownst to nearly everybody, even those closest to him, Andrew Johnston was a superhero. His influence was as profound as it was largely unseen. Like the hero of Miller's Crossing, Tom Regan, Andrew managed to re-order large parts of his universe without anyone being the wiser.

Andrew—the Time Out New York film and TV critic and House Next Door contributor who died Oct. 26 at age 40—was, to put it mildly, not a glamorous person. Compared to Andrew, Peter Parker was James Dean. He was vaguely birdlike—darting eyes; bobbing head; question mark posture with arms akimbo, as if his body was remembering wings. It was possible to speak to him for minutes at a time without making eye contact, and when his eyes did meet yours, the connection was often brief, even furtive.

And his way of speaking—well, House contributor Sarah Bunting, who interviewed him for the web site she cofounded, Television Without Pity, told me that transcribing an interview with Andrew for her "Ask a TV critic" feature was one of the more difficult assignments she could recall. Andrew didn't talk in a straight line. On a good day, he was serpentine. He interrupted himself, qualified himself, questioned himself, reversed course, even argued with himself. He was his own interrogator. There were moments when it seemed as though you were talking to two people—Andrew Johnston and his questioning subconscious. His sentences had clauses and sub-clauses and sub-sub-clauses. In retrospect it seems not at all surprising that one of his favorite shows was Deadwood, a series built around monologues that could go on for a minute or longer, and only when you looked at them on the page did you realize that the whole monologue was one long sentence.

Reading Andrew in the pages of Time Out or in the weekly series TV recaps that he did for The House Next Door was a different proposition. He was an incisive, direct critic who managed to combine baseline assessments of a work's entertainment value with a wide-ranging, free associative view of the work's place within the culture—the forces that inspired it, and the message that it hoped to convey.

Here's one brief passage from Andrew writing about one of his favorite series, Mad Men, for The House Next Door—reviewing an episode entitled "The Benefactor", he segues from a summary of the episode and its function within the show's ongoing storyline into a discussion of narrative itself.

After the fairly ground-shaking events of "Flight One"—Pete's Dad dies! We learn the deal with Peggy's baby! Duck emerges as a full-blown Bad Guy!—I was somewhat surprised to find that "The Benefactor" was basically a standalone with only the tiniest bit of follow-up to the previous episode. But then the more I thought about it, the more I realized something: Almost all of Mad Men's "big" episodes, "Flight One" included, are basically standalones. This approach is a reversal of the main TV model of the 1990s, and proof of just how much series creator Matthew Weiner learned from working on The Sopranos.

"I recently absorbed most of Maps and Legends, Michael Chabon's collection of critical essays on genre fiction, in addition to rereading Scott McCloud's Understanding Comics, so I hope you'll forgive me for getting a bit academic and pin-headed here. Basically, for most of the history of television, dramas were divided into two varieties: Serials (from Peyton Place through Dallas, Dynasty, etc) and series that were basically collections of short stories about the characters (pretty much every crime/medical/science fiction series you can think of). The main similarity is that in both types of series, the characters never really changed.

"Much of this has to do with the nature of the short story, the form that has arguably influenced episodic TV drama more than any other. I'm sure readers of this column will be able to come up with other examples (right now, all I'm coming up with are Ernest Hemingway and John Updike), but sequential short stories following a single protagonist are far less common in the realm of "serious" fiction than in the genre world—and genre fiction characters, like those on TV, are far less likely to experience real change."

I can't say if, in his multi-year battle with cancer, Andrew experienced real change beyond, obviously, the physical; I tend to think he didn't experience change in the simplistic, formulaic sense—becoming a different person, a better person. If anything, Andrew's stubborn fight against his own mortality amplified the man he was—made his fighting spirit, his generosity, his life force not just more visible, but impossible to ignore.

Andrew was a terrific person when I first met him in 1998, when we were young Turks inducted into the Baby Boomer-dominated New York Film Critics Circle. And he continued to be a great person during the whole time I knew him. He could be spacey and impatient, even hotheaded, and as I alluded to earlier, he was often a hard person to read—opaque at times, even Sphinx-like. But beneath those surface characteristics was a rock-solid sense of values and a deep love for, and appreciation of, other driven people. He believed in talent and originality and singularity of artistic expression, and he dedicated his professional and personal life to seeking out those qualities, nurturing them and doing all he could to help anyone who exemplified them find an audience.

Andrew was an influential critic in his 20s, when he started writing about movies for Time Out New York. A lot of men would have been content to enjoy that position and be done with it, but not Andrew. He used whatever sway he had to bring other new voices into the fold. Just in the past week, Mike D'Angelo, film columnist for Esquire, credited Andrew with helping establish him as a working film critic by recommending him as his replacement when Andrew left Time Out for a brief and unhappy stint at US Magazine. So did Bilge Ebiri, who writes for New York Magazine and Nerve.com; Andrew gave Bilge his first paying job as a critic and continued to send work his way up until the weeks prior to his death, when he asked Bilge to review the new DVD box set of Budd Boetticher westerns for Time Out.

Many, many more working critics have their own versions of these anecdotes. They all end the same way: Andrew gave me my start.

As chief film critic for Time Out—and later, upon his return to the magazine as the editor and chief critic of the TV and DVD section—Andrew made a point of farming out reviews and feature articles to talented but largely unknown writers whom he met in online forums, at parties, in bars, waiting on line at film screenings. Andrew gave me my first paying job as a magazine editor last year, when he asked me to fill in for him as TV and DVD editor of Time Out while he was off having yet another round of surgery and chemotherapy.

At no point did Andrew tell me of the good works he did for other people. It's an aspect of his life that we're all very slowly discovering as we talk about him, about his life and work and what it meant.

Andrew's taste was defiantly his own. He didn't take his cues from anybody—no mean feat for a guy who landed a high-profile job as a New York Film Critic in the 1990s, when critics of earlier generations dominated the profession and insisted, explicitly or implicitly, that younger critics acknowledge the works they enjoyed during their youth in the '60s and '70s as the be-all and end-all. Andrew's taste in film and TV was eclectic; he loved classic horror films, the signposts of mid-century European art cinema, and yes, the high watermarks of American film that made Pauline Kael's heart go pitter-pat.

But at the same time, he demanded that contemporary work be given a fair hearing, even equal weight, and that we not look down our noses at work created for mediums that were considered disreputable, or from source material that was not from the accepted canon. During his first year in the New York Film Critics' circle, he was part of a group of critics agitating to give Terrence Malick's first film in 20 years, The Thin Red Line, as many awards as possible. It ended up getting best cinematography and best director in a year that Steven Spielberg's Saving Private Ryan dominated critical discourse.

Five years later, as chairman of the NYFCC, Andrew pushed hard to give Peter Jackson's Lord of the Rings movies recognition. The final entry in the trilogy, Return of the King, won Best Picture—a stunning upset that made many of his fellow NYFCC members furious. "I can't believe we gave best picture to a movie about hobbits," one complained. Andrew considered the award not just a deserved accolade for a mammoth and unexpectedly well-executed project, but a bouquet tossed to fantasy and science fiction buffs whose enthusiasms were more often mocked by the critical establishment. The NYFCC award paved the way for Return of the King to sweep the Oscars that year, and for other critics to proclaim their love of the trilogy openly, without the usual qualifiers.

Andrew gave other people permission to be themselves. He believed comic books, videogames and series TV deserved to be evaluated as thoughtfully as feature films at a time when even suggesting such a thing marked one as unserious—as a geek. He encouraged critics his age and younger to stop mindlessly genuflecting to their fathers' and mothers' movies and embrace the new, the now.

Andrew was a booster of great TV, closely following Mad Men, Breaking Bad, The Wire, The Sopranos, Deadwood, Buffy the Vampire Slayer, Battlestar Galactica, Rescue Me, The Office, The Shield, Friday Night Lights and other series worth watching and arguing about. One of his proudest achievements was his championing of Donnie Darko, a film that got lukewarm to baffled reviews when it was released in fall of 2001, soon after the attacks of 9/11. Andrew believed it was a future classic and a present-tense masterpiece, a film whose virtues would eventually be recognized. By writing a rave review for Time Out, then mentioning it again in print every chance he got, Andrew did more than any working critic to usher that film into the modern pantheon.

Every time Andrew underwent cancer treatment, at a juncture where doctors warned him he was very likely not going to make it, he'd emerge on the other side and get a tattoo to celebrate the fact that he was still alive. At the time of his death he was edging into Illustrated Man country. His prize tattoo was inspired by the team slogan of Friday Night Lights "Clear Eyes, Full Hearts, Can't Lose." The screensaver on his laptop and his work computer was Kurt Russell driving that car with the skull and crossbones on the hood from—yep—Death Proof.

Andrew knew deep down that ultimately you can't beat death; sooner or later it always gets you. So he decided to fight as hard as he could and enjoy life while he could. He characterized his cancer as a challenge, almost a dare—a battle he had no choice but to engage. After he had surgery on his spine, he showed me a digital photo of the scar. It looked like the handiwork of Michael Myers from Halloween. I was speechless; he grinned at me and said, "Yeah…It's bigger than I thought it was be. It's already healing up, but I want to show people what it looked like right after. It's pretty awesome."

Three weeks ago, when Andrew's legs started to give out and he was having difficulty even crossing a room, he asked me to go see Nick Cave and the Bad Seeds play Madison Square Garden. It took him 15 minutes to get into the Garden, and he left well before the encore was finished because, as he put it, "I don't want to get trampled by the mob." He'd often follow up an especially difficult surgery by going to Austin and spending a couple of weeks catching live bands and hitting barbecue joints. He celebrated his 40th birthday a few months ago, shortly after finishing a brutal round of chemo, at a Brooklyn beer garden, downing pint after pint of dark beer and eating enough sausage to kill a grizzly.

The last time I saw Andrew, he was in a hospital bed, recovering from all sorts of punishing treatments, including an MRI. He said he wanted to see the season finale of Mad Men, so I got him a screener and we watched it on my laptop. His reflexes were slow—sometimes he couldn't shuttle back and forth to re-check lines of dialogue as precisely as he would have liked—but his mind was sharp, catching scenes and images that were callbacks to scenes from earlier in the season, or from last season—details I never would have caught on my best days.

On the way out, I said goodnight to him and told him that one of the great pleasures of this time was seeing how his mother, Martha, doted on him, doing everything she could to make his ordeal as comfortable as possible. "You've got a hell of a mom, Andrew," I said. Andrew blushed a little, then grinned at me. "Yeah," he said. "I know."

Andrew endured the loss of a brother, Stewart, who was killed in 1990 in India. He told me about it on the night of the memorial service for my wife. I had no idea he'd been through such trauma. It clearly was hard for him even to mention it, and in subsequent years, we never discussed it again. He told me that the grieving process is like climbing a mountain, reaching what you think is the top, then realizing you've got another peak to climb, then another, then another. I asked him, "Do you ever reach the top?" And he said, "No. But you learn to like hiking."

Andrew Johnston taught me how to live. I love you, brother.

A Brooklyn-based filmmaker and a former critic for The New York Times, The Star-Ledger and New York Press, Matt Zoller Seitz is the editor emeritus of The House Next Door. He posts videos on YouTube under the name InsomniacDad.