Hilda Roderick Ellis Davidson FSA (born Hilda Roderick Ellis; 1 October 1914 – 12 January 2006) was an English folklorist. She was a scholar at the University of Cambridge and The Folklore Society, and specialized in the study of Celtic and Germanic religion and folklore.

A graduate of Newnham College, Cambridge, Davidson was a Fellow at Lucy Cavendish College, Cambridge, throughout much of her career. She specialized in the interdisciplinary study of Celtic, Anglo-Saxon and Old Norse religion and folklore, on which she was the author of numerous influential works. Davidson was a prominent member of The Folklore Society, and played an active role in the growth of folklore studies as a scientific discipline. Throughout her career, Davidson tutored a significant number of aspiring scholars in her fields of study, and was particularly interested in encouraging gifted women to pursue scholarly careers.

Hilda Ellis Davidson was born in Bebington, Cheshire, England, on 1 October 1914, the daughter of Henry Roderick (a stationer) and Millie Cheesman Ellis.

Davidson received a First Class Honours degree in English, archaeology and anthropology from Newnham College, Cambridge. She gained both her M.A. (1939) and PhD (1940) at Newnham. Her PhD thesis was on Old Norse religion. Davidson would eventually become proficient in many languages, including Old Norse, Norwegian, Swedish, Danish, Icelandic, Russian, Latin and German.

Davidson began her academic career as an assistant lecturer in English at Royal Holloway, University of London (1939–1944). Her first book The Road to Hel: A Study of the Conception of the Dead in Old Norse Literature (1943), published under her maiden name Hilda Ellis, utilized archaeological evidence for the examination of death in Norse paganism. This was a pioneering approach, as the study of Old English and Old Norse in British academia at the time was strictly concerned with literary and linguistic concerns. Davidson's utilization of an interdisciplinary approach to the study of Old Norse religion was to become a strong characteristic of her research. From 1945 to 1955 she was a lecturer in the extramural department at Birkbeck, University of London.

Although encountering a significant amount of opposition to her attempt at combining archaeological and philological evidence for the study of Old Norse and wider Germanic religion, Davidson continued with her research. In subsequent years, she published a number of influential works, including The Sword in Anglo-Saxon England (1962), Gods and Myths of Northern Europe (1964), Pagan Scandinavia (1967), and Scandinavian Mythology (1969). With Peter Gelling, she published The Chariot of the Sun (1969). During this time, Davidson contributed many papers to scholarly journals, where she often drew on her knowledge of myth, legend and folklore to interpret archaeological finds. She received a research award from the Leverhulme Trust in 1964 for her work in the Soviet Union.

From 1968 to 1971, Davidson was a Calouste Gulbenkian Research Fellow at Lucy Cavendish College, Cambridge. After 1971 she was Lecturer, and after 1974 Fellow, in Anglo-Saxon, Norse and Celtic at Lucy Cavendish. She was vice president at Lucy Cavendish from 1975 to 1980. She was deeply involved in the expansion and modernization of Lucy Cavendish. During this time she also published several influential works, including The Viking Road to Byzantium (1976) and The History of the Danes: Saxo Grammaticus (1979–1980). At Cambridge Davidson ran the Cambridge Folklore Group, and was known as an active and lively speaker.

Davidson had joined The Folklore Society in 1949, and was a member of its council (later Committee) from 1956 to 1986, subsequently becoming an honorary member. As a leading member of the Society, she played an active role in restoring the field of folklore studies as a scientific discipline. Davidson was actively involved in encouraging the modernization and democratization of the Society. Notable friends whom she worked with in this regard include Katharine Briggs and Stewart Sanderson. These efforts culminated in the election of Katharine Briggs as president and Venetia Newall as Secretary of the Society in 1967. In the subsequent years, Davidson was publications officer of the society, supervised the newly formed Mistletoe Books series, organized conferences, and edited or co-edited the papers that were produced as a result.

Davidson was herself President of the Society from 1974 to 1976, during which the Society prospered. Its constitution was rewritten, and the output of its journal, Folklore, significantly expanded in both volume and quality. Davidson's efforts to modernize the Society are memorized in her Changes in the Folklore Society, 1949–1986 (1987), which were published originally in Folklore. Apart from her membership in The Folklore Society, Davidson was also a Fellow of the Society of Antiquaries of London.

In her later career, Davidson was particularly interested in exploring themes and beliefs common in both early Celtic and Germanic culture. Books produced as a result include Myths and Symbols in Pagan Europe (1988), Lost Beliefs of Northern Europe (1993), and Roles of the Northern Goddesses (1998). She received the Coote Lake Medal for Folklore Research in 1984. Davidson helped endow the Katharine Briggs Folklore Award in 1982, which she herself received in 1988 for her Myths and Symbols in Pagan Europe (1988).

Davidson also dedicated herself to examining the history of folklore studies itself. In this connection, together with Carmen Blacker, she edited Women and Tradition: A Neglected Group of Folklorists (2000). In 1987, Davidson helped found the Katharine Briggs Dining Club. She organized many of its conferences, and edited the papers that were produced as a result, often in cooperation with Blacker and Anna Chaudhri. In 1988 she published a biography of her friend Katharine Briggs. The last of her editorial projects, A Companion to the Fairy Tale (2003), was conducted in cooperation with Chaudhri.

On 27 December 1943, Davidson married Richard Robertson Davidson, a research scientist, with whom she had two children. Davidson was a member of the Liberal Party and the Church of England. She was actively involved in church life as a churchwarden and bell-ringer.

Davidson died on 12 January 2006. Her funeral was held in St Bene't's Church in Cambridge on 21 January 2006. She was survived by her children, grandchildren and great-grandchildren.

At the time of her death, Davidson had for many decades been a highly distinguished scholar in Old Norse religion and mythology. She helped extend both popular and scholarly interest in the fields of Norse, Germanic and Celtic mythology. She played an important role in the post-war revival of folklore studies, and in establishing the study of British folklore as a scientific discipline. Several of her works were translated into multiple languages, including Swedish, Norwegian, Danish, Dutch and Japanese. Her efforts to encourage interdisciplinary research combining archaeology, literature, folklore and history was highly important. She was a tutor of a large number of scholars in mythology and folklore, and was particularly devoted to encouraging the scholarly careers of gifted women.