Nancy Drew , the girl detective who could pick a lock, play the bagpipes, tap Morse Code in high heels and drive her blue roadster like a Daytona champ, turns 90 next year.

Introduced as “a pretty girl of 16” on the first page of “The Secret of the Old Clock” in 1930, Nancy has inspired generations of readers (Sonia Sotomayor, Oprah Winfrey and Hillary Clinton among them) with her style and pluck. No matter how many bowling balls and candelabras bludgeon her, she keeps sleuthing. Fictional characters like V.I. Warshawski, Veronica Mars and Betty Cooper of “Riverdale” owe her a tip of the cloche hat.

“She’s a force for good, unafraid to speak up, unafraid to challenge authority,” said Melanie Rehak, the author of “Girl Sleuth: Nancy Drew and the Women Who Created Her.”

Over the years, Nancy has aged up and down; her hair has morphed from blond to red to strawberry; she has acquired best friends, Bess Marvin and George Fayne, and a loyal boyfriend, Ned Nickerson. Briefly, her roadster was maroon. Never out of print, she has appeared in more than 250 books and counting, in movies, on television shows, in CD-ROM games. She has been reinvented, in ways that fans have not always embraced, for seemingly every era.