Nathaniel Jarvis Wyeth (January 29, 1802 – August 31, 1856) was an American inventor and businessman in Boston, Massachusetts who contributed greatly to its ice industry. Due to his inventions, Boston could harvest and ship ice internationally. In the 1830s, he was also a mountain man who led two expeditions to the Northwest and set up two trading posts, one in present-day Idaho and one in present-day Oregon.

In the 1830s, he became interested in the Northwest and planned an expedition with Hall J. Kelley. In 1832 he proceeded independently, traveling to Fort Vancouver. Two years later in 1834, he led another expedition, founding Fort Hall in present-day Idaho and Fort William in present-day Portland, Oregon. Unable to succeed commercially against the powerful Hudson's Bay Company, he sold both fur trading posts to it in 1837. At the time, both Great Britain and the United States had fur trading companies, settlers and others in the Pacific Northwest. After they settled the northern boundary in 1846, both forts were considered part of the United States and its territories. After returning to Boston, Wyeth managed his business affairs and amassed a considerable fortune.

The Fort Hall site has been designated a National Historic Landmark and is considered the most important trading post in the Snake River Valley through the 1860s. More than 270,000 emigrants reached it while traveling the Oregon Trail.