Nicolet Jean (1598–1642), a French explorer of North America. He was the first European known to have reached Lake Michigan and Wisconsin. Nicolet came to New France (Canada) about 1618 and lived among French-allied Indians, for whom he later acted as an interpreter. In 1634 Samuel de Champlain commissioned him to find a new passage to the South Sea (Pacific Ocean) and thus to China.

Nicolet entered Lake Michigan from Lake Huron. At the southern end of Green Bay he discovered the Fox River. The Winnebago Indians told him that a portage (overland passage) linked it with "The Great Water." They were referring to the Mississippi system, but Nicolet thought they meant the Pacific. He reported that he had found the long-sought water passage to the Pacific. On his Lake Michigan trip he arranged a peace treaty between the Winnebago and Huron Indians. He then returned to Canada, where he became a fur trader and Indian agent.