Theiss/Mathias Fischbach was born circa 1515 in Oberfishbach, Nassau-Siegen, Germany to Johann Fischbach (c1475-c1546) and died circa 1565 Nassau-Siegen, Germany of unspecified causes. He married Treina (c1515-) .
Children
| Name | Birth | Death | Joined with |
| Thiess Fischbach (c1538-bef1619) | 1538 Nassau-Siegen, Germany | 1619 Freudenberg, Nassau-Siegen, Germany | Lueck (c1540-) |
Siblings
| Name | Birth | Death | Joined with |
| Theiss Fischbach (c1515-c1565) | 1515 Oberfishbach, Nassau-Siegen, Germany | 1565 Nassau-Siegen, Germany | Treina (c1515-) |