| Pierre Lassus | |
| Birth Date: | 11 April 1741 |
| Death Date: | 16 March 1807 (aged 65) |
| Occupation: | surgeon |
| Known For: | surgeon to the daughters of Louis XV |
| Work Institutions: | Institut de France |
Pierre Lassus (11 April 1741 – 16 March 1807) was a French surgeon born in Paris.
He was a one-time surgeon to the daughters of Louis XV, and in 1795 worked with Philippe-Jean Pelletan (1747–1829), Nicolas Dieudonné Jeanroy (1750–1816) and Jean-Baptiste Dumangin (1744–1826) on the autopsy of 10-year-old Louis XVII.
In 1802 he was appointed secrétaire perpétuel of the physical sciences section at the Institut de France. In 1804 he was chosen by Jean-Nicolas Corvisart (1755–1821) as a consultant-surgeon of the Emperor.