So much has been written about James Dean, and his influence looms so large over movies and over popular cultural in general, that it’s always jarring to be reminded that at the time of his death, at the preposterously young age of 24, he had starred in only three films—two of which hadn’t even been released when he died in a car crash on Sept. 30, 1955.

And yet, as iconic a star as Dean has become, much of the public’s view of the brooding young man from Indiana was, in fact, formed not by his singular onscreen presence in Giant, East of Eden or even Rebel Without a Cause, but by a series of remarkable pictures made in early 1955 by the photographer Dennis Stock.

In his 2005 book James Dean: Fifty Years Ago, Stock writes of trying to get the rapidly rising actor, whom he barely knew, to agree to let the photographer chronicle Dean’s return to both New York and Indiana from his new home in Los Angeles.

“The story, as I explained it [to Jimmy],” Stock wrote, “was to reveal the environments that affected and shaped the unique character of James Byron Dean. We felt a trip to his hometown, Fairmount, Indiana, and to New York, the place of his professional beginnings, would best reveal those influences. . . . I would solicit an assignment guarantee to cover expenses. The obvious magazine to approach was LIFE. . . . It took only a week for LIFE to approve the assignment.”

The photographs that Stock produced during his time with Dean captured an introspective, intensely self-analyzing (and occasionally self-absorbed) artist—albeit one who could, at times, also be self-deprecating almost to the point of parody.

LIFE, meanwhile, ran a number of the pictures in its March 7, 1955, issue, under the headline, “Moody New Star.” East of Eden was about to open, and would make Dean a household name. Less than six months later, mere weeks before the release of Rebel Without a Cause, the phenomenally talented, category-defying actor would be dead—and would pass into legend.

Here, LIFE.com remembers the too-short life and brilliant, violently truncated career of a true Hollywood original, as seen through the lens of a brilliant photographer, and asks: What would it have felt like?

What would it have felt like to receive one’s weekly issue of LIFE magazine in the mail in, say, a small town in New Mexico, or New Hampshire—or in Boston or Chicago or Miami, for that matter—what would it have felt like to open it up, and encounter in its pages that startling shot of a haunted-looking Dean, cigarette in his mouth, stalking through Times Square in the rain? There’s a kind of desolate romance in that picture—a bracing, bleak solitude that evokes the story of every young, driven, creative person who has ever moved to a city to pursue a dream.

What did it feel like to see that picture, for the very first time, long before the man in the raincoat with the inscrutable, lopsided grin had become something far larger than a mere movie star?

It’s difficult—close to impossible—to encounter any pictures of note that we’ve known for decades and see them, really see them, as if looking at them for the first time. But if we’re able to suspend for even a brief moment all we’ve come to know of James Dean, or all we think we know of James Dean, then the pictures in this gallery offer more than just a diversion, more than just a reminder of what was lost when Dean was killed in that car wreck six decades ago. They offer us a chance to experience the jolt that must have raced through countless readers in the late winter of 1955, as they gazed at Stock’s portraits of this beautiful, thrilling young star, all the while knowing, knowing, that he would be with them, starring in movies, for years to come.