Renato Casaro’s hand-drawn art has hooked movie audiences around the world since the 1950s. Tarantino and Stallone are big fans. One secret to his success? “You can’t cheat.”TREVISO, Italy — Renato Casaro was taking a trip down memory lane, a long journey in a career that extends from the 1950s, when Rome was known as Hollywood on the Tiber, to the last decade when Quentin Tarantino asked for his help on the 2019 film “Once Upon a Time … in Hollywood.”“I constantly adapted,” said Mr. Casaro, who is a few days short of his 86th birthday. “That’s why I kept working when others stopped.”Over more than six decades, his hand-drawn movie posters have hooked audiences into theaters, acting as abridged portends of the delights to come.“The important thing was to capture the essential: that moment, that glance, that attitude, that movement that says everything and condenses the entire story. That’s the hard part,” Mr. Casaro said, adding an admonishment: “You can’t cheat. You can’t promise something that isn’t there.”The essential might translate into the tender embrace he depicted on the poster for a 1955 Russian ballet version of “Romeo and Juliet.” Or it could be a terrified eye lit by a candle for the 1969 thriller “The Haunted House of Horror.” Or maybe an impossibly brawny Arnold Schwarzenegger brandishing a sword as “Conan the Barbarian” in 1982.Although his art has been seen by untold millions, Mr. Casaro himself is mostly invisible, his work largely uncredited (save for his neatly printed signature discreetly tucked in a margin). He is known primarily to collectors, and to the many producers and directors who sought him out to plug their pictures.The Santa Caterina complex in Treviso, one of the venues for the exhibition of Mr. Casaro’s work.Alessandro Grassani for The New York Times“It’s a bit of a sore spot,” Mr. Casaro said during a recent interview in Treviso, the northeastern Italian city where he was born and where he returned to live a few years ago. As far as he knew, he said, he’d been credited in the end titles just once, in 1984, by Sergio Leone for his work on “Once Upon a Time in America.”But now Mr. Casaro is getting his moment in the limelight as Treviso celebrates his art through an ambitious retrospective: “Renato Casaro. Cinema’s Last Poster Designer. Treviso, Rome, Hollywood.”“We’re very proud to celebrate the maestro who gave emotions to so many people,” said Treviso’s mayor, Mario Conte. Many of Mr. Casaro’s posters had become icons, “forever lodged in our memories,” he said.The show’s title traces the trajectory of Mr. Casaro’s career — from crafting movie posters as a teenager in exchange for free tickets to Treviso’s Garibaldi Theater, to the days when extravagant sword-and-sandal films set in ancient Rome were shot in the modern Italian capital, to his brushes with A-list Hollywood actors.Mr. Casaro said he’d been “born with a paintbrush in my hand,” a natural talent who got better “with a lot of experience.”He moved to Rome in 1954, just as it was becoming a favorite of international filmmakers, who took advantage of the city for its unparalleled setting, the production expertise at Cinecittà Studios and the allure of rising local stars like Sophia Loren.He found work at a well-known advertising design studio specializing in movie posters.Mr. Casaro, who is about to turn 86, working in his studio this month in Treviso.Alessandro Grassani for The New York Times“You learn on the job,” said Mr. Casaro, who eventually went out on his own. “You have to be able to draw everything, from a portrait to a horse to a lion.”It really was la dolce vita, he recalled.“We’d come out of the trauma of the war, and Rome was full of life,” he said, with movie stars and tourists swelling the swanky restaurants of Via Veneto. He was out of that league, but he tried to sneak into the hottest places.“We lived on the margins, but come on, it was marvelous to be young and go to Rome and discover this world,” he said in the deconsecrated church of Santa Margherita, one of the venues for his exhibition. His mother, he noted, was less thrilled with his vocation and location. Growing up in provincial Treviso, Rome might as well have been on another planet. “She thought Rome was the city of perdition,” he said. “She cried, she fretted, ‘I’ve lost my son.’”In Rome, he worked constantly. Roberto Festi, the curator of the exhibition, estimated that during this first phase of his career, he was making about 100 posters a year.To better understand the mood of a film, Mr. Casaro often went on the set. Sergio Leone wanted him in New York to witness a key moment in “Once Upon a Time in America.”“They were filming the scene where the youngest boy gets killed,” Mr. Casaro recalled, an image that eventually evolved into the movie poster. “It was stunning, and the highlight of the first part of the film.”At the exhibition in Treviso. Conan and Bond were among Mr. Casaro’s subjects. Alessandro Grassani for The New York TimesThe turning point in his career, which brought attention outside Italy, came when Dino De Laurentiis hired him to make the poster for the 1966 blockbuster “The Bible: In the Beginning…” It was the start of a long-lasting collaboration with Mr. De Laurentiis, and the friendship helped put him in Hollywood’s sights.Mr. Casaro drew the posters for the Conan trilogy, breakthrough films for Mr. Schwarzenegger, who in 1982 was known mostly as a bodybuilder. For the first film, Mr. De Laurentiis, one of the producers, told Mr. Casaro to focus on the actor’s face, not just his muscles. “Dino wanted to launch him,” Mr. Casaro said. “He knew that Schwarzenegger would explode as an actor.”Another big star of the day, Sylvester Stallone, loved how Mr. Casaro had depicted him in his role as the troubled Vietnam vet Rambo. “Stallone said that I had entered into his soul,” Mr. Casaro said.Mr. Casaro’s early style, which he described as “impressionistic,” became increasingly realistic in the 1980s when he began using an airbrush. That made his technique more photographic but also “more magical,” he said.A poster for Rambo III. Mr. Casaro said Sylvester Stallone told him he had “entered into his soul.”Alessandro Grassani for The New York Times“When he began working in hyper-realism, that was the big change,” said Nicoletta Pacini, the head of posters and movie memorabilia at Italy’s National Museum of Cinema. “That was pure Casaro, and others began to copy him.”The artist isn’t sure how many movie posters he created in total but estimates it’s close to 2,000.“He always understood the spirit of the film” creating images that were “special and distinctive,” said Carlo Verdone, one of Italy’s most famous comedic actors and directors who hired Mr. Casaro to make posters for several films. Mr. Casaro stopped making posters in 1998, when the taste for hand-drawn images had waned in favor of digital and photoshopped renderings. Not for him, he said.He shifted his focus to African wildlife drawings — and elaborate re-workings of famous Renaissance paintings populated with movie stars.In a reimagining of Michelangelo’s “Last Judgment,” Marilyn Monroe holds court. “She’s always been the ultimate myth for me,” Mr. Casaro said. “With all her weaknesses, she still represents a special moment in the history of cinema.”Mr. Casaro showing a drawing of Marilyn Monroe. “With all her weaknesses, she still represents a special moment in the history of cinema,” he said of her.Alessandro Grassani for The New York TimesThen, out of the blue, Mr. Tarantino called, asking for posters in a vintage spaghetti-western style for “Once Upon a Time … in Hollywood,” the director’s love letter to 1960s Los Angeles.He designed two posters featuring Leonardo DiCaprio, who plays an on-the-way-out actor who goes to Italy to make spaghetti westerns and revive his career. One of the posters is for a fictional film called “Kill Me Now Ringo, Said the Gringo.”“Those films always had incredible titles,” Mr. Casaro laughed.Mr. Tarantino sent him a signed photo of Mr. DiCaprio posing for the poster with a message that reads: “Thanks so much for your art gracing my picture. You’ve always been my favorite.”For Mr. Casaro’s admirers, the Treviso exhibition is long overdue.“The history of art has tended to marginalize posters because they were conceived for the masses, and the illustrators were seen more as craftsmen,” said Walter Bencini, who made a documentary about Mr. Casaro. “But movie posters can be popular art in the true sense of the word, because they’re part of the collective imagination but also evoke so many personal feelings tied to specific moments.”The feelings evoked in his poster for “The Sheltering Sky,” lushly filmed by Bernardo Bertolucci in 1990, make it one of Mr. Casaro’s personal favorites. “It captures the mystery,” he said, “the notion of immersing oneself in the desert.”If movies are primarily about entertainment, then Mr. Casaro’s summary of his career is apt.“I had fun,” he said. “A lot of fun.”Mr. Casaro in his studio. “I constantly adapted,” he said of his long career.Alessandro Grassani for The New York Times More