Hennepin, Louis (1640–1701?), a Roman Catholic friar and explorer of North America. Hennepin accompanied La Salle on his exploration of the Great Lakes region and wrote popular, but distorted, accounts of his adventures. In 1680 he discovered and named the Falls of St. Anthony, at the site of present-day Minneapolis, Minnesota.

Hennepin was born in Flanders. He joined the Recollects, a branch of the Franciscan order, and in 1675 sailed for Canada to become a missionary at Fort Frontenac (now Kingston, Ontario). In 1678 he became La Salle's chaplain. In 1679 Hennepin and other members of the La Salle expedition boarded the Griffon, the first sailing ship on the Great Lakes, and traveled on Lake Erie, Lake Huron, and Lake Michigan. They then proceeded inland, and built Fort Crèvecoeur near what is now Peoria, Illinois. From here La Salle sent Hennepin and two companions to explore the upper Mississippi River.

The three men were taken captive by Sioux Indians, but were rescued by Sieur Duluth. Hennepin returned to France in 1682. In 1690 he was expelled by Louis XIV for unknown reasons. His first book, A Description of Louisiana (English translation, 1880), is fairly accurate and includes the first printed description of Niagara Falls. In his next book (translated as Hennepin's New Discovery, 1903), he falsely claimed to have preceded La Salle in traveling down the Mississippi River to its mouth.