| Herménégilde Boulay | |
| Constituency Mp: | Rimouski |
| Parliament: | Canadian |
| Predecessor: | Jean Auguste Ross |
| Successor: | Joseph-Émile-Stanislas-Émmanuel D'Anjou |
| Term Start: | 1911 |
| Term End: | 1917 |
| Birth Date: | March 20, 1861 |
| Birth Place: | St. Donat, Canada East |
| Death Date: | May 18, 1942 |
| Nationality: | British subject |
| Party: | Conservative Party (1908–1917) Unionist (1917–1921) Conservative Party |
| Occupation: | farmer manufacturer merchant trader |
Herménégilde Boulay (March 20, 1861 – May 18, 1942) was a Canadian politician, farmer, manufacturer, merchant and trader. He was elected to the House of Commons of Canada as a Member of the historical Conservative Party in 1911 to represent the riding of Rimouski. He was defeated in the election of 1908, 1917, 1921 and 1930. The elections of 1917 and 1921 he contested in Matane.
Born in St. Donat, Canada West, Boulay served as mayor of Sayabec, Quebec, before entering federal politics.