| Monika Cassens | |
| Birth Name: | Monika Thiere |
| Birth Date: | 1953 2, df=yes |
| Birth Place: | Prestewitz, Bezirk Cottbus, East Germany |
| Country: | East Germany Germany |
| Handedness: | Left |
| Bwf Id: | A1A95887-223E-4E6B-9C6A-D19BACD4C7C6 |
Monika Cassens (Thiere, born 28 February 1953) is a German former badminton player.
She started her career in Tröbitz. For this club she won 15 national titles. After her marriage to Claus Cassens, she changed to SG Gittersee, a badminton club in Dresden. During her career she won 101 international tournaments. She won 6 Polish Open titles in a row in women's singles and women's doubles, and six titles in mixed doubles. In 1990 she won the Malta International.