Before she married Monaco's Prince Rainier in 1956 and became real-life royalty, Grace Kelly was living a different kind of fairy tale: that of a talented young movie star who was, for all intents and purposes, a Hollywood princess.
In the fall of 1953 — after charming Gary Cooper in High Noon, and just before appearing in two hugely entertaining Hitchcock classics, Dial M for Murder and Rear Window — the cool blonde actress sat for LIFE photographer Loomis Dean for a series of stunning portraits that, for reasons lost to time, never made it into print.
Dean caught up with Kelly again in February 1954. The year was shaping up to be a busy one for the young star: In the span of a few months, she would add five films to her short but impressive resume, including the previously mentioned Hitchcock films and the movie for which she won the Oscar for Best Actress, The Country Girl.
Kelly seemed destined for a long career as a movie star. But in April 1955, she met Prince Rainier at the Cannes Film Festival, and her life took a dramatically different path. Accepting his proposal of marriage, she became princess of the principality of Monaco in 1956, retiring from Hollywood at just 26 years old. (That's not a misprint; she retired from the movies at the absolute height of her career and of her popularity as an actress and star.)
Before she hit it big in films, Kelly was a player on the small screen. "Her TV plays have ranged from Berkeley Square to F. Scott Fitzgerald's The Rich Boy" LIFE noted in 1952. "In one hectic 13-day period she played three roles: a college girl on Tuesday, a rich girl on Sunday and, eight days later, a country schoolteacher. Usually cast as a wholesome ingénue, she was happily surprised a few weeks ago to find herself on [the mystery-thriller series] Lights Out playing a provocative music hall singer in short skirts and black mesh stockings."
"The basis for her success," LIFE instructed its readers, "is her combination of freshness, ladylike virtue and underlying sex appeal that has led two of her directors to compare her with the early Ingrid Bergman."
High praise — and for once, amid the incessant grind of Hollywood's star-making machinery, wholly deserved (if perhaps just the slightest bit patronizing). Here, on the 30th anniversary of Grace Kelly's death at the far-too-young age of 52, LIFE.com presents a series of photos — none of which originally ran in LIFE magazine — from her sessions with Loomis Dean.
Her good friend and Rear Window co-star Jimmy Stewart eulogized Kelly as "just about the nicest lady I ever met. Grace brought into my life ... a soft, warm light every time I saw her, and every time I saw her was a holiday of its own." These revealing pictures from the mid-1950s capture that soft, warm light — as well as Kelly's famed, singular beauty — as completely as any portraits ever made of the beloved, short-lived star.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter @lizabethronk.