| Wilhelm Kettler | |
|---|---|
| Duke of Courland and Semigallia | |
 | |
| Duke of Courland | |
| Reign | 1587–1617 |
| Predecessor | Gotthard Kettler |
| Successor | Friedrich Kettler |
| Born | 20 June 1574 Mitau, Duchy of Courland and Semigallia |
| Died | 7 April 1640 (aged 65) Kucklow, Duchy of Pomerania |
| Burial | Ducal crypt in the Jelgava Palace |
| Spouse | |
| Issue | Jacob, Duke of Courland |
| House | Kettler |
| Father | Gotthard Kettler |
| Mother | Anna of Mecklenburg |
| Religion | Lutheranism |
Wilhelm Kettler (20 June 1574 – 7 April 1640) was the Duke of Courland, a Baltic German region in today's Latvia. Wilhelm ruled the western Courland portion of the Duchy of Courland and Semigallia, while his brother Friedrich ruled the eastern Semigallia portion.