| Pieter Nassen | |
| Birth Date: | 16 January 1944 |
| Birth Place: | Riemst, Belgium |
| Currentteam: | Retired |
| Discipline: | Road |
| Role: | Rider |
| Ridertype: | Sprinter |
| Proyears1: | 1967 |
| Proyears2: | 1967–1971 |
| Proyears3: | 1972 |
| Proyears4: | 1973 |
| Proyears5: | 1974 |
| Proyears6: | 1975 |
Pieter Nassen (born 16 January 1944) is a Belgian racing cyclist.[1] He rode 5 editions of the Tour de France, and won the intermediate sprints classification in 1971.[2] He also won three stages of the Vuelta a España.