| Nationality: | German |
| Birth Date: | 15 November 1965 |
| Birth Place: | Hamburg, West Germany |
| Height: | 1.9m (06.2feet) |
| Weight: | 800NaN0 |
| Strokes: | Freestyle |
Stefan Pfeiffer (born 15 November 1965 in Hamburg) is a former freestyle swimmer from Germany. At the 1984 Summer Olympics in Los Angeles he won the bronze medal in the 1500 m freestyle event. Four years later at the 1988 Summer Olympics in Seoul, Pfeiffer earned another medal, this time silver, in the same event.