Otto III, Duke of Brunswick-Harburg | |
|---|---|
 Otto III, Duke of Brunswick-Harburg | |
| Born | 20 March 1572 Harburg |
| Died | 4 August 1641 (aged 69) Harburg |
| Noble family | House of Guelph |
| Spouse(s) | Hedwig of Brunswick-Wolfenbüttel |
| Father | Otto II, Duke of Brunswick-Harburg |
| Mother | Hedwig of East Frisia |
Otto III, Duke of Brunswick-Lüneburg, Lord of Harburg (20 March 1572 in Harburg – 4 August 1641 in Harburg) was a titular Duke of Brunswick-Lüneburg and ruler of the apanage Brunswick-Harburg.