Helen Gurley Brown, the original “Cosmo girl,” paved the way for Carrie Bradshaw, Lena Dunham and sexy, single girls everywhere. When she published her infamous Sex and the Single Girl in 1962, Ms. Brown created the concept of the New York single girl and joined the ranks of leaders of the women’s liberation movement, promoting the idea that women could enjoy sexual freedom before (or without) settling down with Mr. Right. Ms. Brown became editor in chief of Cosmopolitan magazine in 1965, and she spent the next 32 years transforming the failing periodical into a staging ground for women’s liberation, fun, sex and flair. Cosmo’s covers inevitably featured a pouting model with dazzling tresses and a panther’s grace. Between articles on great sex, more sex and now sex, Ms. Brown created features like “Why Don’t You …,” which encouraged women to buy themselves the shoes, clothes and possessions they desired, without waiting for a man to do so. Ms. Brown, who tripled the magazine’s circulation and introduced international editions during her tenure, famously proposed the idea that women can have it all—love, sex and money. Just like she did.