| Christian August I, Duke of Schleswig-Holstein-Sonderburg-Augustenburg | |
| Noble Family: | House of Oldenburg |
| Father: | Prince Frederick William of Schleswig-Holstein-Sonderburg-Augustenburg |
| Mother: | Sophia Amalia of Ahlefeld |
| Spouse: | Frederikke Louise Danneskiold-Samsøe |
| Issue: | Frederick Christian I, Duke of Schleswig-Holstein-Sonderburg-Augustenburg |
| Birth Date: | 4 August 1696 |
Christian August I, Duke of Schleswig-Holstein-Sonderburg-Augustenburg (4 August 1696 - 20 January 1754) was a son of Frederick William of Schleswig-Holstein-Sonderburg-Augustenburg, who was himself a son of Ernest Günther.
He served as provost of the cathedral chapter in Hamburg. Later, he became governor of the Danish island Als, then General of the Infantry and Colonel of the royal guards in Denmark. In 1731, Christian August I succeeded his childless uncle Ernest August.
He married Frederikke Louise (1699–1744), the daughter of Count Christian Gyldenløve of Danneskiold-Samsøe. They had the following children: