Hilaire du Berrier (November 1, 1906 – October 12, 2002) was an American barnstorming pilot, mercenary adventurer, journalist, and spy. He wrote for a number of publications, mostly right-wing and far-right, including his own monthly newsletter. He was born as Harold Berrier on November 1, 1906, in Flasher, North Dakota. His ancestry was either Huguenot or Polish. His father was a fur businessman; he died when Berrier was nine. As a teenager, Berrier was sent to the Pillsbury Military Academy, but was expelled one month before graduating. His mother sent him to an art school in Chicago. He found employment as a commercial artist in Chicago, working part time for ad agencies and department stores. He started working at Heath School of Aviation, an early aviation manufacturer. At 20, he quit his job to become a barnstormer. Trained by aviation stuntman Dick Powell, du Berrier started his own circus, Du Berrier's Flying Circus, which travelled around the Midwest. Du Berrier had a few close misses (including, du Berrier said, a rival barnstormer's sabotage of a rope ladder that du Berrier would hang off during stunts). It closed after the start of the Great Depression and the enactment of new federal flight safety rules. In 1931, du Berrier traveled to Paris with his uncle, a former congressman, who had been appointed a U.S. representative to the Paris Colonial Exposition. After arriving in France, he was given the registered name of Hilaire, which he went by afterward. He joined the social circle of the Lafayette Escadrille World War I pilots. His barnstorming career caught the attention of Charles Sweeny. According to du Berrier, he met exiled Spanish king Alfonso XIII by chance while walking down the Rue de Rivoli, and said he had a "lifetime follower" after that. He also joined the far-right Action Française movement. He moved to Monte Carlo where he managed a nightclub, and after it closed, he worked for a perfume business. His mother died in 1935, leaving him an inheritance.