When LIFE published Edward Steichen's 1928 portrait of Greta Garbo on its cover in January 1955, the Swedish-born actress was still one of the most famous film personalities in the world—despite not having appeared in a movie for more than a decade. She was then, and a quarter-century after her death she remains, a singular screen presence: a mysterious, alluring star of both silent films and the early, Golden Age of "talkies" who retired from acting when she was just 35 years old.
Today, of course, she's almost a punch line for people who have never even seen one of her movies (I want to be alone), while for true film buffs she is comparable only with the likes of Katharine Hepburn and Bette Davis when discussing genuine, enduring screen icons.
Here, on her birthday—she was born Sept. 18, 1905, in Stockholm, Sweden, and died in New York City in April 1990, at the age of 84—LIFE.com remembers Garbo, the legend, as seen through the lens of a master. Steichen's photo (originally published in Vanity Fair in 1929) is, in many ways, the image that countless people have in mind when they think of Garbo. Her gaze is at-once so direct and so unreadable that it's difficult to know if she's offering the viewer a challenge, or an invitation. All we know for sure is that here is a rare sort of beauty: beguiling, disquieting, inscrutable.