James Owen Dorsey (October 31, 1848 – February 4, 1895) was an American ethnologist, linguist, and Episcopalian missionary in the Dakota Territory, who contributed to the description of the Ponca, Omaha, and other southern Siouan languages.

[1] He lived 27 months as a missionary in Nebraska and South Dakota, learning the difficult (for English speakers) Siouan language of the Ponca and Omaha Indians.

In the early years, he tried to link those languages with Hebrew, in the mistaken theory, shared by many scholars at the time, that Native Americans were among the Lost Tribes of Israel.

"[2] In 1878, in the formative period of the Bureau of American Ethnology (BAE) as part of the Smithsonian Institution, the director John Wesley Powell engaged Dorsey to return to Nebraska to compile dictionaries of the Omaha and Ponca languages.

In addition, he studied several tribes along the Oregon coast, where he compiled materials on the Athabaskan (also called Dene), Coosan, Takilman, and Yakonan language families or "stocks", some of which were spoken by small groups of people.