| Birth Date: | 15 September 1946 |
| Birth Place: | Bremen, Allied-occupied Germany |
| Height: | 1.87m (06.14feet) |
| Weight: | 80kg (180lb) |
| Sport: | Swimming |
| Club: | Wasserfreunde Wuppertal |
Rainer Jacob (born 15 September 1946) is a retired German swimmer who won a silver medal in the 4 × 100 m freestyle relay at the 1970 European Aquatics Championships. He finished sixth in the same event at the 1972 Summer Olympics.
His mother, Gisela Jacob-Arendt, and uncle, Heinz Arendt, were German Olympic swimmers.