Wilhelm Mannhardt (March 26, 1831, Friedrichstadt – December 25, 1880, Danzig) was a German scholar and folklorist. He is known for his work on Baltic mythology, as a collector, and for his championing of the solar theory.
He carried out field work despite poor health. His work was a forerunner of James Frazer's; like Frazer, his theories have subsequently been heavily criticised.
- Letto-Preussische Götterlehre (1870),
- Wald- und Feldkulte. Band 1: Der Baumkultus der Germanen und ihrer Nachbarstämme: mythologische Untersuchungen (reprint)
- Wald- und Feldkulte. Band 2: Antike Wald- und Feldkulte aus nordeuropäischer Überlieferung erläutert (reprint)