Nora Ephron, an essayist and humorist in the Dorothy Parker mold (only smarter and funnier, some said) who became one of her era’s most successful screenwriters and filmmakers, making romantic comedy hits like “Sleepless in Seattle” and “When Harry Met Sally...,” died Tuesday night in Manhattan. She was 71.

The cause was pneumonia brought on by acute myeloid leukemia, her son Jacob Bernstein said.

In a commencement address she delivered in 1996 at Wellesley College, her alma mater, Ms. Ephron recalled that women of her generation weren’t expected to do much of anything. But she wound up having several careers, all of them successfully and many of them simultaneously.

She was a journalist, a blogger, an essayist, a novelist, a playwright, an Oscar-nominated screenwriter and a movie director — a rarity in a film industry whose directorial ranks were and continue to be dominated by men. Her later box-office success included “You’ve Got Mail” and “Julie & Julia.” By the end of her life, though remaining remarkably youthful looking, she had even become something of a philosopher about age and its indignities....