Why LIFE never published the gold mine of photos seen in this gallery after Marilyn became a bona fide superstar remains a mystery.
In a 1999 interview with Digital Journalist, Clark described how, in 1950, he received a call from a friend at 20th Century Fox about “a hot tomato” the studio had just signed: one Marilyn Monroe.
“She was almost unknown then, so I was able to spend a lot of time shooting her,” Clark recalled. “We’d go out to Griffith Park [in Los Angeles] and she’d read poetry. I sent several rolls to LIFE in New York, but they wired back, ‘Who the hell is Marilyn Monroe?’”