| Célestin Sieur | |
| Birth Date: | 1860 12, df=y |
| Birth Place: | La Chapelle-en-Lafaye, France |
| Death Place: | Paris, France |
| Nationality: |  France |
| Fields: | Medicine |
| Alma Mater: | University of Bordeaux |
| Known For: | Sieur's sign |
Célestin Sieur (La Chapelle-en-Lafaye, 27 December 1860 – Paris, 12 June 1955) was a French physician specializing in ENT surgery. The Sieur's sign is named after him.