Neil Simon, who died Sunday at the age of 91, was a compulsive quipster as a writer, but he was no ordinary funnyman.

Yes, in his early comedies he tried to make sure there was one potential laugh line per minute, and succeeded so brilliantly at amusing his audiences that he became the most successful playwright America has ever seen and is likely ever to see.

But his comedies are hardly light and frothy. Rather, they are riven with darkness, bitterness, sadness and disappointment. You might say, in fact, that Simon turned what W.H. Auden called “the age of anxiety” into box-office gold.

In his play “Broadway Bound,” Simon’s lightly fictionalized brother Danny explains to the young would-be writer that the essence of all comedy is conflict. A guy “wants money, he wants a girl, he wants to get to Philadelphia. When someone tries to stop him from getting money or a girl or getting to Philadelphia, that’s conflict.”

Even when the characters in Simon’s best plays are happy, they’re not happy. They’re funny because they’re miserable — and because their misery is so, well, interpersonal. They live in perpetual conflict.

His most successful work concerns the conflicts that arise when two wildly different people — one emotionally undisciplined and carelessly fun-loving, the other tightly controlled and deeply neurotic — share uncomfortably close quarters.

In 1964’s “Barefoot in the Park,” a square lawyer marries a kooky free-spirited recent college grad who wants him to lighten up even as he wants her to become a more responsible person. In 1977’s “The Goodbye Girl,” a kooky free-spirited actor who sleeps in the nude is forced to share a small apartment with the single mother of a 10-year-old girl.

And in his greatest work, 1965’s “The Odd Couple,” the fussy Felix is invited to live with his dearest buddy, Oscar the divorcé, after his wife throws him out — and after three weeks the two men are ready to kill each other.

Most of Simon’s work hasn’t aged well because the conflicts are so passé, and are dismissed by cognoscenti because his comedy is implicitly disapproving of efforts to subvert bourgeois morality.

His first play, 1961’s “Come Blow Your Horn,” is about a New York City playboy whose father is titanically disapproving because he’s not married. He’s a “bum,” in his father’s eyes, and his father is terrified he will lead his impressionable younger brother down the path to bum-dom.

As for “Barefoot in the Park,” it’s clear Simon thinks the kooky wife’s lack of inhibition is a sign of immaturity she must grow out of if her marriage to the responsible adult lawyer is to succeed.

Even “The Odd Couple” ends with a comic restoration of some form of conventional social order. Even though he’s sent Felix packing because his insistence on cleanliness was driving Oscar insane, the unsanitary Oscar tells his poker-playing buddies to stop messing up his apartment.

Simon had a view of his native New York City that was essentially neoconservative — another mark of his bleak worldview entirely at odds with the image of him as a jokester.

In his 1970 nightmare movie comedy “The Out-of-Towners,” two Ohioans come to a New York in the midst of a general strike and spend 24 hours being conned, robbed, kidnapped and generally mistreated by a collapsing city.

The next year, in a play called “The Prisoner of Second Avenue,” middle-aged Mel is fired from his advertising job and finds himself slowly being driven mad by a garbage strike, crazy neighbors and an apartment burglary of the sort all too common in New York at the time.

His strangest play, “God’s Favorite,” is the story of Job recast as the torments afflicting a Long Island businessman with a wayward son. Simon wrote it after his first wife Joan died of cancer at the age of 38, and it concludes with God’s messenger preparing to visit all the calamities he inflicted on Job on his son.

This was his darkest joke in a career centered on a worldview that was anything but light and frothy. Neil Simon is not a writer for our time because he did not give voice to outrage, or to calls for revolutionary change. All his characters really want is a break.

And a Klonopin.