William Tufnell Le Queux (/ləˈkjuː/ lə-KYOO, French: [ləkø]; 2 July 1864 – 13 October 1927) was a French-English journalist and writer. He was also a diplomat (honorary consul for San Marino), a traveller (in Europe, the Balkans and North Africa), a flying buff who officiated at the first British air meeting at Doncaster in 1909, and a wireless pioneer who broadcast music from his own station long before radio was generally available; his claims regarding his own abilities and exploits, however, were usually exaggerated. His best-known works are the anti-French and anti-Russian invasion fantasy The Great War in England in 1897 (1894) and the anti-German invasion fantasy The Invasion of 1910 (1906), the latter becoming a bestseller.

Le Queux was born in London. His father was a French draper's assistant and his mother was English. He studied art under Ignazio (or Ignace) Spiridon in Paris. He carried out a foot tour of Europe as a young man before supporting himself writing for French newspapers. In the late 1880s he returned to London where he edited the magazines Gossip and Piccadilly before joining the staff of The Globe as a parliamentary reporter in 1891. In 1893 he abandoned journalism to concentrate on writing and travelling.

His partial French ancestry did not prevent him from depicting France and the French as the villains in works of the 1890s, though later he assigned this role to Germany.

Le Queux mainly wrote in the genres of Romance, mystery, thriller, and espionage, particularly in the years leading up to World War I, when his partnership with British publishing magnate Lord Northcliffe led to the serialised publication and intensive publicising (including actors dressed as German soldiers walking along Regent Street) of pulp-fiction spy stories and invasion literature such as The Invasion of 1910, The Poisoned Bullet, and Spies of the Kaiser. These works were a common phenomenon in pre-World War I Europe, involving fictionalised stories of possible invasion or infiltration by foreign powers; Le Queux's specialty, much appreciated by Northcliffe, was the German invasion of Britain. He was also the original editor of Lord Northcliffe's War of the Nations.

In 1908 Johan Millen approached William Le Queux about finding funding for what later became known as the Parker Expedition to Jerusalem. Le Queux wrote about it in his autobiography Things I Know about Kings, Celebrities and Crooks (1923). He wrote

One day, during the five years I lived at the Hotel Cecil, a waiter brought me a card bearing the name of Broström, with an address in Stockholm. A tall, middle-aged, clean-shaven Swede was ushered in, and handed me a letter of introduction from a friend, a certain Baroness Nernberg, who is one of the leaders of Society in the Swedish capital. This letter explained that my visitor was a well-known civil engineer in Sweden, that he was highly trustworthy, and that he had a very curious disclosure to make to me. We sat down, and certainly what he told me caused my eyes to bulge. Briefly, it was that a friend of his, a certain Professor Afzelius (sic), at Abó University, had discovered in the original text of the Book of Ezekiel preserved in the Imperial Library at Petrograd a cipher message that gave the whereabouts of the concealed treasures from King Solomon's temple.

The individual he calls Afzelius was in fact Valter Juvelius. After he was approached Le Queux says that he took the papers to a Dr Adler, a friend who was also the Chief Rabbi, to verify the documents. Le Queux says that Adler came back and said that there was something to the documents. On the basis of the positive response to the cypher documents Le Queux approached Sir C. Arthur Pearson, the proprietor of the Standard newspaper for funding for the expedition to Jerusalem. He described what happened next:

To this he most generously acceded, and an initial sum was agreed between us for its cost. I was to head the expedition to Palestine. That afternoon I walked along the Strand full of suppressed excitement.