Jacques Le Tort (c. 1651 – c. 1702) was a French-Canadian fur trapper, trader, explorer and entrepreneur who spent much of his life in the Province of Pennsylvania engaged in the fur trade. He collaborated with other French-Canadians living there at the time, including Peter Bisaillon and Martin Chartier, as well as the future mayor of Philadelphia, James Logan. By the late 1690s he had become wealthy and somewhat notorious; the Provincial authorities had his wife arrested on suspicion of conspiring with the French to take control of Pennsylvania territory, although no charges were ever proven. He disappeared following a trip to England in 1702 and is presumed to have died at sea. His wife Anne Le Tort and his son James Le Tort took over his business after his death.

Le Tort was born in Bonnétable (dept. of Sarthe). He became a Huguenot refugee who arrived in New France in 1686. A letter of recommendation dated 1 January 1686 gives his age as 35, so it is inferred that he was born in 1651. The letter also refers to him as "Sieur" ("Lordship"), a title generally used for landowners of elevated social status. Several Pennsylvania documents refer to him as "Captain Le Tort," although the reasons for this are unclear. His wife Anne, his young son James, and two uncles came from France with him, spending a few months in London before embarking for Quebec. A second son, Francis was born soon after their arrival. One source also lists a daughter, Ann Margaret, born before 1715.

Le Tort was hired by Daniel Coxe and Matthias Vincent, who attempted to establish a colony of French Huguenots in East and West Vincent Township, Pennsylvania and who planned to create an empire in the Indian trade on the south shore of Lake Erie. In 1696 Provincial Governor William Markham wrote that "Le Tort is a Protestant, who was sent over in the year 1686 with a considerable cargo and several French Protestants, of whom he had the charge, by Doctor Cox, Sir Mathias Vincent...to settle 30,000 acres of land up the Schuylkill, that they had bought of Mr. Penn." The colony failed because Huguenot families did not want to move from Philadelphia to wild lands along the Schuylkill and Susquehanna Rivers, although Le Tort and his wife Anne built a homestead there, leasing 400 acres from Coxe and establishing a trading post on the Schuylkill, near the present site of Spring City, Pennsylvania. Coxe founded the New Mediterranean Sea Company in hopes of expanding his business, but could not secure authorization from William Penn, as the British were concerned that competition would reduce fur prices and affect their profits. In 1687 Coxe sent a large quantity of trade goods from England to stock Le Tort's trading post, writing to his agent in Philadelphia:

Sir, I had ordred a Cargoe of Sortable Commodities...which Cargoe Cost here in England att best hand above six hundred pounds...I desire you would lett Monsieur Le Tort and those on my Plantation know that...I have sent all necessaries both for themselves & Indian Trafick and I have ordred my Agent to intrust Mr Le Tort with goods to a considerable vallue...Mr Le Tort hath desired mee to intrust him wth some goods & hath faithfully promised returne of furrs to a good vallue in ye Spring.

Anxious to establish relations with Native American tribes further west, Coxe encouraged Le Tort and his neighbors to make contact with communities in the Ohio Valley and along the upper Mississippi.

In 1687 or 1688 Le Tort and two other men, probably Huguenots, made their way by canoe up the Susquehanna River, portaged to the Allegheny River, descended the Ohio River to the Mississippi and ascended the "great yellow river," probably the Missouri River. Little is known of the journey as the venture was kept secret to prevent interference by the government of New France or by rival businesses, and Le Tort's journal and map were eventually lost. Coxe later wrote:

I Encourag'd severall to attempt further discoveries whereupon three of my Tenants in a birchen Canoa went up School Kill (a River comes into Delaware River at Philadelphia) above one hundred Miles then a Branch of the same River to its head, & Carrying their Canoa over some small Hills entred the Great River Hohio, which after a great Course of Six hundred Miles Joynes the Mischacebe [Mississippi], and going up that River went up the great yellow River three days Voyage, which River Comes from ye Hills which separate New Mexico from Carolana. They went & Returned Through above forty Nations of Indians who all treated them very kindly & gave them many furs for Indian Trade they Carried with them. I had from them a Large Journall written & a Large Mapp, very Exact, abating the want of Latitudes which [they] had not skill nor Instruments to Take.

Coxe published a report which he submitted in 1719 to the Lords of Trade, but which does not describe the events of the journey or name the three explorers. Le Tort's journal and the map were loaned to William Penn and disappeared. One of Le Tort's two companions on this journey may have been his fellow countryman Peter Bisaillon, who had traveled down the Mississippi in 1686 with Henri de Tonti. In 1688 Le Tort hired Bisaillon to assist him at his trading post in Pennsylvania.