With its Simon & Garfunkel soundtrack, mordant dialogue and bursts of sexual tension, “The Graduate” was a generational touchstone, launching the movie career of Dustin Hoffman, earning director Mike Nichols an Oscar and turning a character’s one-word piece of career advice — “plastics” — into a punchline.

Based on a novel by Charles Webb, the 1967 film foreshadowed Hollywood’s turn toward a more youthful audience and made more than $100 million at the box office, drawing rave reviews for its story of a disaffected college graduate (Hoffman) who is seduced by a married woman (Anne Bancroft) and falls in love with her daughter (Katharine Ross).

But for all its success, Mr. Webb largely distanced himself from “The Graduate,” which featured a Buck Henry and Calder Willingham screenplay that lifted much of the dialogue from his book. “It’s something that I cannot shake,” he once said of the novel. “It has defined my whole life. I just want to run away.”

Mr. Webb, who became famous but not wealthy from “The Graduate,” went on to write a slew of novels while championing an anti-materialist philosophy and living in poverty. He and his wife, Eve, gave away most of their possessions and worked odd jobs, moving between campgrounds, trailer parks, nudist colonies and a Motel 6 before settling in England.

“Millions and millions were made from ‘The Graduate,’ and here I am,” Mr. Webb told the BBC in 2006, amid a flurry of news coverage about his dire financial straits. “Searching around for a couple of quid to buy my sandwich — people love that.”

He was 81 when he died June 16 at a hospital in Eastbourne, England, more than a decade after publishing “Home School,” a sequel to “The Graduate” that helped him pay off some of his debts. The novel was dedicated to his friend Jack Malvern, a journalist for the Times of London who confirmed Mr. Webb’s death and said the cause was related to a blood condition.

Mr. Webb was 24 when “The Graduate” was published in 1963. Like its protagonist, Benjamin Braddock, he had grown up in the Los Angeles suburbs and graduated from a small Eastern college — though he insisted his character’s affair with an older woman, the Mrs. Robinson character played by Bancroft, was not autobiographical.

“It was an aberrant fantasy of mine that popped out,” he told Britain’s Observer newspaper in 2005. “I was at home after college, like the character in the film. My father was a doctor and had couples over to the house to play bridge. There was a wife of one of the doctors who came over and at the sight of her my fantasy life became supercharged.”

In part, Mr. Webb said, he wrote “The Graduate” to impress his mother, who was always reading. “But it didn’t work” — his parents disapproved of their son’s literary ambitions, at least until the movie became a hit — and Mr. Webb struggled to find his niche as an author, living for a time in Hollywood with his wife, Eve, a model for the Elaine Robinson character whom Benjamin falls for in the novel.

“We thought there was a great fraternity waiting for us,” he later told The Washington Post. “There wasn’t.” Disenchanted, he gave away his tickets to “The Graduate’s” premiere, then returned the keys to his $35,000 Los Angeles bungalow soon after buying it. Owning the house, Mr. Webb later told People magazine, “was just unexplainably oppressive.”

Mr. Webb professed to have little interest in wealth or material possessions. He had sold the movie rights to his novel for a flat fee of $20,000 and never shared in the film’s profits or in the proceeds from subsequent stage adaptations. He donated the book’s copyright to the Anti-Defamation League and went on to sell or donate nearly everything else he had as well, including art by Robert Rauschenberg and Andy Warhol, a $65,000 home in the Berkshires and another house outside New York City.

For a time, he and his family lived in a ’68 Volkswagen bus, crisscrossing the country and parking wherever they could. The Webbs home-schooled their two children and, although they divorced in the early 1980s — in protest of the institution of marriage — remained together, supporting themselves by washing dishes, cleaning houses, picking fruit, clerking at Kmart and presiding over a nudist camp in New Jersey.

“In all fairness, I think Charles and I have gone overboard — because of our upbringing,” his partner and former wife, the daughter of prep-school teachers, told the Associated Press in 1992. “It was devoid of goals or any ideal of doing something for society. We were taught that the only contribution anybody could make was to make money.”

Writing remained Mr. Webb’s focus. He continued working even while going 19 years without publishing a book and seemed to view literature the same way the protagonist of his novel “Booze” (1978), about an alcoholic artist who paints only oranges, viewed art.

“I know pretty well why I’m an artist, it’s the one way I can seal off my past,” Mr. Webb’s character says in the novel. “I don’t have to achieve fame or recognition or succeed in a commercial way but what’s important for me is that I keep doing it, keep painting, and hold on to that feeling which goes along with putting the paint on the canvas.”

“Nothing else matters,” he added. “When people tell me I should do more to get established I don’t argue with them because they can’t understand it’s enough to do the painting itself and it’s all I have and all I need.”

Charles Richard Webb was born in San Francisco on June 9, 1939, and grew up in Pasadena, Calif., where his father worked as a heart specialist. “I have blocked out almost everything that happened to me in childhood,” he later told the Sunday Telegraph, “because I just remember it as being one endless depression.”

Mr. Webb was sent to boarding school and studied history and literature at Williams College, then an all-male school in Massachusetts, where he received a bachelor’s degree in 1961. While in school, he met Eve Rudd, a student at nearby Bennington College.

They married in 1962 and soon sold off their wedding gifts, horrifying family members. (Eve, an artist, later changed her name to Fred, explaining that she aimed to express solidarity with a support group for men with low self-esteem.)

Mr. Webb wrote “The Graduate” with help from a Williams College creative writing grant and apparently found a publishing house with help from his mother. She knew a top editor at New American Library, Arabel Porter, who suggested the manuscript to a colleague, Edward Burlingame. He was shocked by what he read.

“I couldn’t believe my eyes,” Burlingame said in a phone interview. “It was absolutely terrific. I went in the next day and explained, ‘It’s really odd, it’s very different and I think we should take it.’ ” Mr. Webb, he added, had “an extraordinarily good ear for dialogue,” and the novel “captured a sense of dislocation that the young at that time had about society and what was going to become of them.”

Critics were less enthusiastic.

“ ‘The Graduate’ is a fictional failure,” wrote New York Times book critic Orville Prescott. “It raises questions about the psychological motivation of its hero and makes no effort to answer them.” Still, he wrote, Mr. Webb had “created a character whose blunders and follies just might become as widely discussed as those of J.D. Salinger’s Holden Caulfield.”

Prescott’s review attracted the attention of Lawrence Turman, then a 36-year-old producer who optioned the movie rights for $1,000 and convinced Nichols to direct. He was turned down by major studios for nearly two years before securing financing and finding a suitable screenwriter, Henry, who added the “plastics” line while retaining much of the novel’s dialogue. (“Mrs. Robinson, you are trying to seduce me. . . . Aren’t you?”)

Mr. Webb took little credit for the movie’s success. He hired a lawyer to block the words “by the author of ‘The Graduate’ ” from appearing on the cover of his next book, which he considered “exploitative” marketing. Few of his later novels drew critical attention, although “The Marriage of a Young Stockbroker” (1970) was adapted into a movie the next year starring Richard Benjamin.

By 2000, Mr. Webb had immigrated to England, where he said he wanted to see whether he could write a British character. He broke his long publishing drought with “New Cardiff” (2001), about an English artist recovering from heartbreak, which was adapted into the movie “Hope Springs” (2003), starring Colin Firth, Heather Graham and Minnie Driver.

Although the book received strong reviews, Mr. Webb said he increasingly struggled to care for Fred, who was diagnosed with clinical depression. He was near eviction when he published “Home School” (2007), which followed his “Graduate” characters into the mid-1970s and saw Mrs. Robinson try to seduce a school principal to help Braddock and his children.

“I sort of thought it would be my final bow to fiction,” Mr. Webb told the New York Post, “to go back to the beginning to find the ending. And then on to something else.”

Fred died last year. They had two children: John, a Russia expert at the data firm IHS Markit, and David, a performance artist who once cooked and ate a copy of “The Graduate” with cranberry sauce, apparently to his father’s delight. Complete information on survivors was not immediately available.

Mr. Webb’s decision to take a flat fee for “The Graduate” was sometimes ridiculed, with critics noting that he could have earned millions of dollars if he had taken a percentage of the movie’s profits or held on to the copyright from his novel. But while he struggled to pay his rent in recent years, he insisted that getting rich would have been far from a blessing.

“If I’d had $100 million it wouldn’t have taken me that much longer [to spend] than $20,000, and that would have been a whole lifetime’s work getting rid of that much,” he told the blog Thoughtcat in 2006. “I think I would’ve been bitter to get that much money,” he added with a smile. “I think I’d be a bitter old man at this point. I’m sure I’d still be shoveling it out the door.”