“So pretty, so pregnant, so pointless, tragic,” chipped in Evan Dando, the frontman for the Lemonheads.

A sun-dappled Deneuve. A star-spangled Bardot.

Oh, what might have been.

Ms. Tate, known for her saucerlike hazel eyes and once-in-a-generation ability to fill out a minidress, was only beginning to emerge as a screen and style icon when she became a household name for the grisliest imaginable reason. In 1969, the 26-year-old starlet, then more than eight months pregnant, was murdered in her hillside Los Angeles home, along with her unborn son and four others, by followers of Charles Manson.

Image In a hippie headband. Credit... Archive Photos/Getty Images

While top billing eluded the “Valley of the Dolls” actress in life, the honey-blond siren has enjoyed a posthumous renaissance, embraced as a ’60s style avatar by a new generation of style blogs, Pinterest boards and fashion spreads, not to mention a recent Off Broadway show and a lavish photo hagiography by her sister Debra Tate due next month. The actress’s second life online got a major boost recently with a widely dissected conspiracy theory involving “Mad Men,” which some speculate may be building toward a tragic Tate-style climax.

Certainly, Ms. Tate had not disappeared from public consciousness in the 45 years since her death. The ghastly “Helter Skelter” murders have been replayed endlessly in cable documentaries, made-for-TV movies and books, including “Restless Souls: The Sharon Tate Family’s Account of Stardom, the Manson Murders, and a Crusade for Justice,” by Alisa Statman and Brie Tate, Ms. Tate’s niece, from 2012.