Ernest Günther I of Schleswig-Holstein-Sonderburg-Augustenburg was a Duke of Schleswig-Holstein of its Sonderburg line. He was the first to have his ducal seat in Augustenborg Palace, which he built and named in honor of his wife. He ruled from 1647 until his death in 1689.
- Occupation
- aristocrat
- Citizenship
- Kingdom of Denmark
- Born
- October 14, 1609
- Died
- January 18, 1689
