| Otto IV of Schaumburg | |
| Birth Date: | 1517 |
| Death Date: | 21 December 1576 |
| Death Place: | Bückeburg |
| Nationality: | German |
Otto IV of Schaumburg (1517 - 21 December 1576) was a German nobleman. He was a ruling Count of Schauenburg and of Holstein-Pinneberg. He was a son of Jobst I and his wife Mary of Nassau-Siegen, a daughter of Count John V of Nassau-Siegen.
He adopted the teachings of Martin Luther. However, with respect to his elder brothers Cologne's Archbishop-Electors Adolphus III (reg. 1547–1556) and Anthony I (reg. 1557–1558) he refrained from open confrontation. In 1559 he officially began the Reformation in Schauenburg and Holstein-Pinneberg. These areas remained Lutheran throughout the Counter-Reformation and into modern times.
Otto first married Mary (*1527–1554*), daughter of Duke Barnim XI of Pomerania-Stettin. Mary and Otto had four sons:
In 1558 Otto married a second time, with Elisabeth Ursula (*1539–1586*), a daughter of Ernest I, Duke of Brunswick-Lüneburg. Elisabeth Ursula and Otto had two daughters and one son: