Sure, we all loved Lucy, but which one? The rubber-faced Lucy Ricardo of her classic TV sitcom, I Love Lucy? That goes without saying. But what about Lucille, the struggling but determined Hollywood starlet who spent two decades lingering in B-movie purgatory? Or the powerful Ms. Ball, the behind-the scenes TV pioneer and the medium's first major female executive?
Truth is, Lucille Ball lived several fascinating lifetimes, many of them captured by LIFE's photographers on her way up the showbiz ladder. She was the vice president of Desilu Productions, making her television's first female mogul. The strain of running a business with her husband and longtime onscreen foil, Desi Arnaz, and Desi's drinking ultimately doomed the partnership. The couple divorced in 1960, and Ball bought Arnaz out of the business in 1963. Lucy went on to star without Desi in hit sitcoms The Lucy Show (1962-68) and Here's Lucy (1968-74). Desilu, meanwhile, remained a prolific producer of classic 1960s shows like The Untouchables, Mission: Impossible and Star Trek.
Here, LIFE.com presents photos—none of which ever ran in LIFE—of Lucille Ball, including at least one surprisingly sultry 1942 portrait (slide #1) by John Florea, made when Ball was known as "Queen of the B's" for the string of sub-par films that had failed to make her a star. Years of dues-paying hard work are apparent in her eyes. And yet, there is something sweetly defiant, too, about her look: a sense that, with a little luck, her big break is just around the corner.
Man, was it ever.
Liz Ronk, who edited this gallery, is the Photo Editor for LIFE.com. Follow her on Twitter at @LizabethRonk.