They were largely anonymous and unsung, sons of immigrants, restless and creative minds, storytellers, dreamers. They invented an entire universe that, almost a century later, stands as a tentpole of American popular culture, though only recently has their work attracted the interest of museum curators. And Jack Kirby was perhaps the greatest of them all.

Over a six-decade career, Kirby created or co-created some of Marvel Comics’ most fabled heroes: the Fantastic Four, the Incredible Hulk, Captain America, Iron Man, the Avengers, the X-Men, and the groundbreaking Black Panther. But of equal significance was the inner complexity of his characters. Kirby transformed superheroes from two-dimensional cops with capes into layered, conflicted individuals. The first-ever retrospective of his trailblazing work, “Jack Kirby: Heroes and Humanity,” opened last week at Los Angeles’s Skirball Cultural Center.