Jas Hennessy & Co., more commonly known as Hennessy, is a French cognac house with its headquarters in Cognac, France. The company sells about 50 million bottles annually worldwide, making it the largest cognac producer, supplying more than 40% of the world's total cognac shipments. The company is owned by Moët Hennessy, which in turn is owned by LVMH (66%) and Diageo (34%).

The Hennessy cognac distillery was founded by the Irish Jacobite military officer Richard Hennessy in 1765. His son James Hennessy gave the company the name Jas Hennessy & Co in 1813. In the 1970s, Kilian Hennessy, a fifth-generation direct descendant of Hennessy, became the CEO of Hennessy, succeeding his first cousin Maurice-Richard. Kilian Hennessy spearheaded the company's 1971 merger with Moët et Chandon, which created Moët Hennessy.

Moët Hennessy merged with Louis Vuitton in 1987, creating one of the world's largest luxury brand conglomerates, Louis Vuitton Moët-Hennessy, or LVMH. In 1988, a management crisis led to Bernard Arnault, owner of the haute couture house Christian Dior, taking over the group with the support of the Irish brewery Guinness. Kilian Hennessy remained on the company's advisory board until his death in 2010 at the age of 103.