Over his long, provocative career, the artist Billy Apple changed his name, registered it as a trademark, branded products with it, had his genome sequenced and, finally, arranged to have his cells extracted and stored so that they might survive forever even if he could not. He died on Sept. 6 at his home in Auckland, New Zealand, at 85.

The cause was esophageal cancer, said Mary Morrison, his wife and collaborator.

He was born Barrie Bates in Auckland but became Billy Apple in London after graduating, barely, from the Royal College of Art in 1962, one of a rebellious cohort that included David Hockney and R.B. Kitaj.

By 1964 he was in New York City (subletting a loft on the Bowery from the sculptor Eva Hesse) and showing his work. His cast bronze, half-eaten watermelon slice was one of many objects included in “The American Supermarket,” an early Pop spectacle at the Bianchini Gallery on Manhattan’s Upper East Side, where one could buy artist’s versions of real products: a painted turkey by Roy Lichtenstein, candy made by Claes Oldenburg and Campbell’s soup cans signed by Andy Warhol. The gallerist took orders on a grocer’s pad.

“He was a conceptual artist in the most fundamental sense,” said Christina Barton, a university museum director and art historian who is the author of “Billy Apple® Life/Work,” a biography 10 years in the making and published in 2020. “He was committed to living the idea in every minute of every day. He never stopped being ‘Billy Apple,’ which of course is a total invention.”

Mr. Apple went on to work in neon, enchanting some reviewers like Robert Pincus-Witten of Artforum magazine, who described Mr. Apple’s rainbows as “sensuous neon impersonations.” But city inspectors were not charmed. In 1966, when Mr. Apple was 27, they unplugged a show of his at the Pepsi Gallery, in the lobby of the Pepsi-Cola Building at Park Avenue and 59th Street, saying the pieces weren’t wired to code.

The show’s opening had been so well attended that it caused a traffic jam. One attendee was Tom Wolfe, who later panned Mr. Apple’s pieces in New York Magazine — “they’re limp … they splutter,” he wrote. (Mr. Wolfe was writing about the artistry of commercial neon sign makers and poking fun at the art world in the process.)

It was a riotous time. Mr. Apple and his peers, the early Pop and conceptual artists, were engaged in all sorts of shenanigans intended to upend notions of what might be considered art and where and how it might be presented.

Their art-making methods — Mr. Apple went through a tidying phase, washing windows, scrubbing floor tiles and vacuuming up the dirt on his studio’s roof — were not always well received. His “Roof Dirt” piece, which came in the form of an invitation in 1971, prompted John Canaday of The New York Times to write that it “belongs to an area of art‐related activity in which nothing but the word of the artists makes the difference between a put‐on and a seriously offered project.”

Mr. Apple then turned to less festive practices, like saving tissues from his nosebleeds and toilet paper from his bathroom activities. When this work was included in a solo show at the Serpentine Gallery in London, some objected, and the police shut it down. But Mr. Apple was no prankster. He was deadly serious about his work, which, besides meticulously documenting his bodily processes, often included renovation and redecorating suggestions to institutions like the Guggenheim. (He proposed getting rid of its planters; the museum ignored him).

Back home in New Zealand, to which he returned for good in 1990, Mr. Apple began exploring, in a variety of work, ideas about the transactional nature of the art market, branding practices, mapping and scientific advances. Among the works was an apple cast from pure gold, Billy Apple coffee and tea (for sale in galleries only) and the “immortalization” of cells from his own body, which are now stored at the American Type Culture Collection and the School of Biological Sciences at the University of Auckland.

Barrie George Bates was born Dec. 31, 1935, the eldest of four children. His father, Albert George Bates, worked for The New Zealand Post. His mother, Marija (Petrie) Bates, was a homemaker who allowed no toys in the house because she didn’t like the mess; Barrie improvised with what he could find in the kitchen cupboards.

He was bullied at school but did well in chemistry and drawing. He worked as a commercial artist in Auckland before winning a partial scholarship to attend the Royal College of Art in London. He asked his girlfriend at the time to write his general studies dissertation, an imagined conversation between Larry Rivers and Vincent Van Gogh at a New York jazz club. Mr. Apple’s biographer, Ms. Barton, said the paper was an early example of what would be his art-making method: outsourcing.

The dissertation allowed him to earn his degree, though he tore up the registrar’s note telling him so and skipped the graduation ceremony. (His classmate Mr. Hockney attended, in a gold lame jacket.)

While in New York City, Mr. Apple worked episodically for the buzzy advertising agencies of the 1960s and ’70s, like Jack Tinker & Partners and Doyle Dane Bernbach. When Marshall McLuhan guest-edited an issue of Harper’s Bazaar (yes, that happened, in April 1968), Mr. Apple was a contributor. He also opened his own gallery, called APPLE.

In addition to his wife, Mr. Apple is survived by his brothers, Colin and Tony, and a sister, Judith Bates Marsden. His marriage to Jacki Blum, an American artist, ended in divorce in 1981. Together for 24 years, Ms. Morrison, who is also an artist, and Mr. Apple married a few days before his death.

In 2016, Mr. Apple donated some of his early career bathroom tissues along with a contemporary fecal sample to a molecular biologist, who was able to determine that nearly half of the bacteria in Mr. Apple’s gut was still present in his body decades later, as The New Zealand Herald reported. It was a boon for science, and Mr. Apple, too, made new work from the study.

Becoming Billy Apple, the artist told an interviewer in 2018, “allowed me to have good subject matter.”

“I could determine what I wanted to do,” he said. “I didn’t have to look outside of myself. I could build my own brand, as the saying goes.”