| Siegfried III, Count of Weimar-Orlamünde | |
| Noble Family: | House of Ascania |
| Father: | Herman I, Count of Weimar-Orlamünde |
| Mother: | Irmgard |
| Spouse: | Sophie of Denmark |
| Death Date: | 1206 |
Siegfried III, Count of Weimar-Orlamünde (1206) was a member of the House of Ascania and a ruling Count of Weimar-Orlamünde.
He was the son of Count Herman I and his wife Irmgard. Herman I was son of Albert the Bear Count of Anhalt, Margrave of Brandenburg and Duke of Saxony.
He was regarded as a supporter of the House of Hohenstaufen. He spent some time in Denmark. He married Sophie (1159 -), a daughter of King Valdemar I of Denmark and had two sons: