Sir Arthur Conan Doyle created the greatest detective in the history of literature, the incomparable Sherlock Holmes. But did you know he brought skiing to Switzerland? He had seen skis in Norway, having taken his wife to Davos for the air, which was believed to be beneficial for tuberculosis sufferers.

Feeling constrained by the deep snow, he had a local carpenter make him a pair of skis and, together with a couple of Swiss, taught himself to ski. While a few others previously had tried tying wooden slats to their shoes, it was Doyle who wrote an article for the Strand magazine, “An Alpine Pass on Ski,” that introduced the concept of abandoning snowshoes for the faster and more practical skis for descending mountains.

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The Swedes Maj Sjowall, a poet, and Per Wahloo, a novelist, famously collaborated on a series of police procedurals about Martin Beck, including “The Laughing Policeman,” which won the Edgar Allan Poe Award as Best Mystery of the Year and was filmed with Walter Matthau. They planed to write 10 novels about the Stockholm cop and did. But did you know that within days of completing the 10th and final novel, Wahloo died?

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Roald Dahl was famous as the author of such children’s books as “Charlie and the Chocolate Factory” and of darkly ironical mystery stories, including the notorious “Lamb to the Slaughter,” which was made into one of the most talked-about episodes of the television series “Alfred Hitchcock Presents.” His book “Someone Like You” was chosen for Queen’s Quorum, a list of the 125 most important mystery story collections of all time.

But did you know he invented the word “gremlin”? As a fighter pilot in the Royal Air Force during World War II, he envisioned an evil little creature that lived in the airplane engine and caused it to malfunction at crucial times. In 1942, he wrote a children’s book called “The Gremlins.”

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Ira Levin is generally known as a writer of horror and science fiction, notably “Rosemary’s Baby” and “The Stepford Wives,” and mystery fiction, most famously “A Kiss Before Dying,” winner of the 1954 Edgar for Best First Mystery, and “Deathtrap,” the longest-running mystery play in the history of Broadway.

But did you know that he wrote the long-running Broadway comedy, “No Time for Sergeants,” and wrote the lyrics for “He Touched Me,” the hugely successful song recorded by Barbra Streisand?

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Even today, thriller writers are complimented by being compared with John Buchan, whose best-selling spy novels include such adventures of Richard Hannay as “Greenmantle,” “The Three Hostages,” and “The Thirty-Nine Steps,” filmed by Alfred Hitchcock in 1935 and still an edgeof-the seat chase story more than 70 years later.

But did you know that the primary thrust of Buchan’s career was military and political, culminating in his being named governor-general of Canada from 1935 until his death in 1940?

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Among lovers of British detective fiction elevated to the level of the novel of manners, no one is held in such esteem as Dorothy L. Sayers. Her Lord Peter Wimsey novels are a staple of every mystery shelf in the English-speaking world. But did you know she created Colonel Mustard for the popular board game Clue?

Soon after becoming one of the first women to graduate from Oxford University in 1920 she took a job with an advertising agency. One of her accounts was Coleman’s mustard, for which she created a campaign that featured cartoon figures of British colonel-types at the Mustard Club, where they lavished praise on Coleman’s.

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Among the most distinguished authors of espionage fiction of the 20th century are W. Somerset Maugham, who wrote the first realistic collection of short stories about a spy, “Ashenden” (1928); Erskine Childers, who wrote the first pure spy novel of the 20th century, “The Riddle of the Sands” (1903); John le Carre, whose “The Spy Who Came in from the Cold” (1963) and George Smiley novels have been well-filmed and never out of print; Graham Greene, who wrote what he called “entertainments” of such high quality that they are regarded as serious literature, even by snobbish critics, notably such classics as “Orient Express” (1933), “This Gun for Hire” (1936), “The Confidential Agent” (1939), “The Ministry of Fear” (1943), and “The Third Man” (1950); and Charles McCarry, America’s greatest espionage writer, the author of such masterpieces as “The Tears of Autumn” (1975) and “The Secret Lovers” (1977).

But did you know that every one of these authors was also a spy? Maugham worked in Russia and Switzerland between the world wars; Childers was a British hero in the Boer War and World War I who later moved to Ireland and was shot as a traitor by an Irish Free State firing squad; Mr. le Carre had a desk job with MI5, at which he met fellow spy novelist John Bingham; Greene, employed by MI6, became friends with the British traitor and Soviet spy Kim Philby, and is reputed to have aided the Soviets with some spying himself, as well as protecting Philby; and Mr. McCarry was a field worker for the CIA for more than a decade.

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One of the famous courtroom dramas ever filmed was “Anatomy of a Murder,” starring James Stewart, Lee Remick, Ben Gazzara, and George C. Scott. But did you know the man who played the judge was Joseph N. Welch, a judge in real life who came to great prominence during the historic Army-McCarthy hearings before the House Un-American Activities Committee?

Whew! I really do know a lot of utterly useless information, don’t I?

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.