Among the best-known police departments in the world — the French Sureté, the Texas Rangers, the Royal Canadian Mounted Police — none is more famous than England’s Scotland Yard.

But, did you know that it got its odd name from its original headquarters building, which had originally been a palace for Scottish kings when they came to visit London?

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One of the most beloved icons in the world of mystery fiction is Nancy Drew. Stronger and smarter than any boy, the intrepid teenage sleuth became a powerful symbol of independent feminism, even serving as inspiration for many mystery writers, including Jane Haddam (Orania Papazoglou) and Sara Paretsky. From the publication of the first book, “The Secret of the Old Clock” (1930), right to the present day with the release of a new film devoted to her exploits, Nancy has demonstrated all the attributes of the thoroughly modern woman.

But, did you know that the famous Carolyn Keene byline was a house name for a literary syndicate, and that Nancy was the creation of a man, Edward S. Stratemeyer, who wrote the first three books in the series before turning the job over to his daughter, Harriet Adams? Stratemeyer also created the Hardy Boys, Tom Swift, and the Bobbsey Twins.

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Mickey Spillane’s first novel, “I, the Jury,” introduced Mike Hammer, who quickly became one of the most popular literary creations of all time. With tens of millions of his books sold, it is no surprise that he became the hero of numerous films, mostly low budget. The relatively little-known Biff Elliot starred as Hammer in the film version of that first novel in 1953.

But, did you know that it was released, for whatever reason, in 3-D? It was surely the only noir film ever produced in that format.

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A cornerstone work in the history of detective fiction is Dashiell Hammett’s “The Thin Man” (1934), which inspired a beloved series of six motion pictures starring William Powell and Myrna Loy, not to mention their dog Asta. The single novel also begat a radio series in the 1940s, two television series, and an achingly dull Broadway musical, which lasted for 80 performances in 1991.

But, did you know that the thin man of the novel’s title refers to the murder victim and had nothing to do with the detective? Hammett, who was tall and extremely thin, posed for the dust jacket of the first edition, but there is nothing in the text to suggest that Nick Charles weighs less than any other tough guy of the era. While the films are noted for their clever and sophisticated dialogue, especially between Nick and his wife, Nora, producing a series of comedies that hold up amazingly well to the present day, the novel was every bit as dark as any of the author’s other noir classics.

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Franklin Delano Roosevelt is frequently referred to as one of the greatest of all American presidents. Running the country through the Great Depression, he created many government programs that served a purpose then, and many of which remain in place today. In spite of crippling polio, he served as Commander-in-Chief during World War II.

But, did you know that he still managed to find the time to plot a mystery novel? He was friends with Fulton Oursler, the editor of Liberty magazine, and he posed the following question to him: “How can a man disappear with five million dollars in any negotiable form and not be traced?” (I guess if I were married to Eleanor Roosevelt I’d have asked the same question.)

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While it is generally described as a science fiction film, “Blade Runner,” is a classic private eye movie that happens to be set in the dystopian future. Ridley Scott directed the stylish tale of a somewhat seedy P.I., Rick Deckard, who is hired to hunt down some androids. The grizzled tough guy is one of the high points of Harrison Ford’s illustrious career.

But, did you know that the first choice to play Deckard was the unlikely Dustin Hoffman?

Yes, I know. I can’t believe it either.

Mr. Penzler is the proprietor of the Mysterious Bookshop in Manhattan and the series editor of the annual “Best American Mystery Stories.” He can be reached at ottopenzler@mysteriousbookshop.com.