| Birth Date: | 1950 4, df=y |
| Birth Place: | Greiz, East Germany |
| Height: | 1.74m (05.71feet) |
| Weight: | 60kg (130lb) |
| Sport: | Swimming |
| Club: | SC Karl-Marx-Stadt |
| Show-Medals: | yes |
Marianne Seydel (born 1 April 1950) is a retired East German swimmer. She competed in the 200 m and 400 m individual medley at the 1968 Summer Olympics and finished sixth in both events.