It’s one of the most iconic images in film history — and no one knows where it is.

The original artwork for “Jaws,” used for both the cover of the Peter Benchley book and the Steven Spielberg film, which came out 40 years ago this summer, has vanished, says artist Roger Kastel.

Kastel was in the offices of publisher Bantam in 1974 when boss Oscar Dystel handed him a copy of the thriller.

“Oscar said to me, ‘It’s going to be a best-seller,’ ” Kastel tells The Post.

Kastel didn’t have to go beyond the first few pages to find the most arresting passage — when young Chrissie Watkins goes skinny-dipping off the coast of Amity, a fictional Northeast resort town, and becomes a snack for a massive great white shark.

“I just thought it was a great visual,” says Kastel, now 83. “I did a very rough sketch for [Bantam art director] Len Leones while we were talking, and he OK’d it. He told me to make the shark larger and more realistic.”

Kastel headed over to the American Museum of Natural History and took a few photos of stuffed sharks waiting to be cleaned. For the swimmer, a photographer friend suggested 24-year-old Wilhelmina model Allison Maher. The shoot was one of her first jobs.

“I knew it was a book cover and that was it,” says the now-model, now named Allison Stern, who married real-estate developer Leonard Stern and is now a prominent philanthropist, with an area named for her at the Central Park Zoo.

She lay across two stools to simulate a swimming motion, and was paid $35.

Stern says she didn’t get recognized despite the poster’s ubiquity — including being on a giant billboard in Times Square.

“If you know me, you can tell it’s me,” says Stern, who has a copy of the poster signed by Spielberg. “But I think everyone assumed the girl swimming was the girl from the movie.”

Kastel painted oil on Masonite, and “Jaws” didn’t take him long. It was likely one of three paintings he completed that month. In his career, he created some 1,000 posters and covers.

“It was a pleasure to do, but I never thought it would be as huge as it is now,” Kastel says.

Bantam allowed the filmmakers to use the paperback’s image as the movie poster, free of charge. The only alteration was to strategically position sea foam over the swimmer’s bare breasts.

“The book company told me how much [the art] helped sell,” says Kastel of the paperback that had moved some 6 million copies by late 1975. “I’ve never heard from anyone in the movies. What really bothered me was that they used the image for merchandising. You see that poster on everything.”

Upon its completion, the work toured bookstores and made other appearances. The last time Kastel saw it was at an American Museum of Natural History illustration show in the 1970s. From there it made its way to La La Land and was never seen again.

“Oscar [who died in 2014] called me years later, and he was trying to get it back,” says Kastel, who now lives in Massachusetts. “He was quite upset about it. I don’t know if it was stolen or thrown out or someone has it.”