Here is a biographical sketch from the William N. Fenton Papers archive at the American Philosophical Society website:
Born in New Rochelle, N.Y., on December 15, 1908, William Nelson Fenton, became a leading scholar of the history and culture of Iroquois Indians. Raised in New Rochelle until the age of 16, he passed his summers on the family farm in western New York state, located midway between two Seneca Indian reservations. Exposed to anthropological work, Fenton’s interests were encouraged by his father and grandfather, friends to Indians there, who assembled a small collection of Indian memorabilia which was later acquired by the Museum of the American Indian.
After receiving his B.A. from Dartmouth in 1931, Fenton attended Yale for graduate study in anthropology. At the end of his first year in New Haven, the Laboratory of Anthropology at Santa Fe awarded him a scholarship for training in field archaeology on the Great Plains of Nebraska and South Dakota, where he took part in his first professional ethnological interviews. Returning to his old home in New York in 1933, Fenton embarked on what would become more than fifty years of field research on the Allegany, Cornplanter, Cattaraugus, and Tonawanda Seneca Reservations and on the Six Nations Reserve in Canada. From 1935 until he received his doctorate in 1937, Fenton also served as a community worker for the United States Indian Service, working principally on the Tonawanda Reservation.
In his first academic appointment in 1937, Fenton introduced anthropology to St. Lawrence University, though he remained for only three semesters before being called to replace J.N.B. Hewitt at the Bureau of American Ethnology (BAE) of the Smithsonian Institution, earning promotion to Senior Ethnologist in 1943. During the war years, he served as a Research Associate of the Ethnogeographic Board and as Secretary of the Smithsonian War Committee. While a member of the Committee on International Relations in Anthropology at the National Research Council (NRC) from 1952 to 1954, he served as the first Executive Secretary of the Division of Anthropology and Psychology. Meanwhile, he was employed as a visiting professor at Johns Hopkins, Northwestern, and Catholic Universities, and at the University of Michigan.
In 1954, Fenton returned to New York State with his wife, Olive (1908-1986), and their three children to become Assistant Commissioner of the New York State Museum and Science Service in Albany, serving as director of the State Museum for thirteen years. In 1968, he abandoned administration and returned to teaching as Research Professor of Anthropology at the State University of New York at Albany. In 1979, the trustees named him Distinguished Professor, and Anthony F.C. Wallace delivered the honorary lecture.
Throughout his career, Fenton’s research centered on the religious ceremonies and customs of the Iroquois, epitomised by his translation (with Elizabeth Moore) of The Customs of the American Indian Compared with the Customs of Primitive Times by Father Joseph François Lafitau, and hy his most influential work, his 1987 book, The False Faces of the Iroquois.
His obituary suggests that his activities were not always appreciated:
He frustrated some tribes by not returning artifacts, insisting museums were necessary safeguards for the items. Some Indian leaders were upset with Fenton for writing about rituals considered to be sacred.
The only book of his which still seems to be in print (at least as far as Amazon.com is concerned) is The Great Law and the Longhouse: A Political History of the Iroquois Confederacy.
I’m not very familiar with Fenton’s work so if you have some insights into his legacy, please contribute in the comments!