| Birth Date: | 17 December 1919 |
| Birth Place: | Amsterdam, Netherlands |
| Death Place: | Soest, Netherlands |
Catharina "Tini" Wilhelmina Wagner (17 December 1919 - 2 June 2004) was a freestyle swimmer from the Netherlands, who represented her native country at the 1936 Summer Olympics in Berlin, Germany.
In 1936 she won the gold medal in the 4 × 100 m freestyle relay, alongside Willy den Ouden, Rie Mastenbroek and Jopie Selbach. In the 100 m freestyle competition she finished fifth and in the 400 m freestyle event she finished seventh.