| Birth Name: | Léopold Adolphe Joseph Marie Willaert |
| Birth Date: | 19 March 1878 |
| Birth Place: | Bruges, Belgium |
| Death Place: | Namur, Belgium |
| Nationality: | Belgian |
| Discipline: | History |
| Sub Discipline: | Church history |
| Education: | Collège Saint-Servais (Liège) |
| Alma Mater: | Catholic University of Leuven |
| Thesis Title: | Les négociations politico-religieuses entre l'Angleterre et les Pays-Bas catholiques, 1598-1625 |
| Thesis Year: | 1905 |
| Doctoral Advisor: | Alfred Cauchie |
| Workplaces: | University of Namur |
Léopold Willaert (1878–1963) was a Belgian Jesuit Church historian with a particular interest in the history of Jansenism.
Willaert was born in Bruges on 19 March 1878. He joined the Society of Jesus immediately after finishing his secondary education at the Collège Saint-Servais (Liège), and for three years studied philosophy at Stonyhurst College.[1] His doctorate in history, supervised by Alfred Cauchie, was completed at the Catholic University of Leuven in 1905. He then briefly taught at St Michael College, Brussels, before commencing theology studies in Leuven.[2] He took his final vows as a Jesuit in 1912, and from 1913 to 1956 taught at what is now the University of Namur. In 1945 he became president of the board of the Royal Library of Belgium. Willaert died in Namur on 31 October 1963.