The Secret of the Unicorn (French: Le Secret de La Licorne) is the eleventh volume of The Adventures of Tintin, the comics series by Belgian cartoonist Hergé. The story was serialised daily in Le Soir, Belgium's leading francophone newspaper, from June 1942 to January 1943 amidst the Nazi German occupation of Belgium during World War II. The story revolves around young reporter Tintin, his dog Snowy, and his friend Captain Haddock, who discover a riddle left by Haddock's ancestor, the 17th century Sir Francis Haddock, which could lead them to the hidden treasure of the pirate Red Rackham. To unravel the riddle, Tintin and Haddock must obtain three identical models of Sir Francis's ship, the Unicorn, but they discover that criminals are also after these model ships and are willing to kill in order to obtain them.
The Secret of the Unicorn was a commercial success and was published in book form by Casterman shortly after its conclusion. Hergé concluded the arc begun in this story with Red Rackham's Treasure, while the series itself became a defining part of the Franco-Belgian comics tradition. The Secret of the Unicorn remained Hergé's favourite of his own works until creating Tintin in Tibet (1960).