| Birth Date: | 12 February 1934 |
| Sport: | Swimming |
Katharine "Kati" Jansen (born 12 February 1934) is a retired German freestyle swimmer who won a bronze medal at the 1954 European Aquatics Championships. She competed at the 1952 and 1956 Summer Olympics in the 100 m and 4 × 100 m freestyle events and finished fourth in the relay in 1956.