Flynn’s career would be difficult to replicate in contemporary Hollywood. As an action hero he was larger-than-life, yet not artificial in the ruling Marvel/DC mode. Unlike most of today’s action moviemakers, his best directors at Warner Bros.—Michael Curtiz and Raoul Walsh—aimed for heights of gusto and grace. They understood the literary beauty of heroism, which wouldn’t fit into “Top Gun’s” agenda. At the magnificent climax of “The Charge of the Light Brigade,” Curtiz superimposes Tennyson’s verse over Flynn’s suicidal gallantry: “When can their glory fade? / O the wild charge they made! / All the world wondered.”

Flynn gave melting-pot moviegoers high-style heroes to love and admire. They could be raffish self-made men, notably Irish-American champ James J. Corbett in Walsh’s go-getter boxing film “Gentleman Jim” (1942), or risk-taking servants of the Crown, such as the Francis Drake-like privateer in Curtiz’s “The Sea Hawk,” whose verbal jousts with Queen Elizabeth are as memorable as the movie’s “Ben Hur”-scale sea battles.

Hollywood’s glamour-industrial complex cannily packaged and promoted Flynn, but he wasn’t a product of the dream factory. Born in Tasmania, Australia, in 1909, to a marine-biologist father and a mother who claimed to be descended from an HMS Bounty mutineer, he was a wild colonial boy—with all the biases and braggadocio that implies. In 1927 he set sail for New Guinea, where he spent five years working as a prospector, trader, hunter, skipper, plantation manager, Cadet Patrol Officer and recruiter of indentured labor.

Laurence Olivier remarked, “When you are young, you are too bashful to play a hero; you debunk it. It isn’t until you are older that you can understand the pictorial beauty of heroism.” Bashfulness was never Flynn’s problem. His daredevil youth had prepared him for the title role in “Captain Blood,” a cynical but virtuous Irish doctor who turns rebel after King James II sentences him to Caribbean slavery. (Curtiz directed.) When Olivia de Havilland, as the niece of a colonial planter, tells Blood, “I believe you’re talking treason,” he replies, “I hope I’m not obscure.” Deadpan impudence became one of Flynn’s trademarks.

In 1942 Flynn was accused of statutory rape by two 17-year-old women. He was tried and acquitted, and his popularity emerged unscathed, but the scandal gradually altered his image and self-image. His humorous self-awareness evolved first into self-parody, then self-revelation. At career’s end he drew on his own alcohol and drug addiction to convey the dissolution and self-loathing of world-weary drunks. Flynn’s early roles fleshed out abstract words—“glory” and “honor”—that Ernest Hemingway had hated. But to Hemingway, Flynn’s performance as Lost Generation lush Mike Campbell in the 1957 adaptation of his 1926 novel, “The Sun Also Rises,” was “the best thing about the film.”

Flynn died two years later, at 50. In his posthumous, playfully titled memoir, “My Wicked, Wicked Ways” (1959), he depicted himself as a hedonist bordering on libertine. Living high—and low—had killed him.

His anarchic sensibility, though, helped fuel his on-screen spontaneity, even in semi-idiotic blockbusters like “They Died with Their Boots On.” In Walsh’s romantic biopic, Flynn’s panache merges with George Armstrong Custer’s: They both leap from comic grandeur to boldness incarnate. The writer Ian Frazier observed, “Custer’s life demonstrates the power of a person having fun.” Frazier theorized that Custer’s superiors “secretly looked up to him”—as perhaps Jack Warner did to his studio’s leading man. Frazier described Custer’s fame as “the victory of fun and myth over complicated history.” Add artistry to the mix, and so is Errol Flynn’s.

Mr. Sragow is the author of “Victor Fleming: An American Movie Master” (2008) and co-wrote the documentary “Fiddler’s Journey to the Big Screen” (2022).