| William IV | |
|---|---|
 Portrait by Barthel Beham, 1533 | |
| Duke of Bavaria | |
| Reign | 18 March 1508 – 7 March 1550 |
| Predecessor | Albert IV |
| Successor | Albert V |
| Co-ruler | Louis X (1516–1545) |
| Born | 13 November 1493 Munich |
| Died | 7 March 1550 (aged 56) Munich |
| Burial | |
| Spouse | Jakobaea of Baden |
| Issue | Albert V, Duke of Bavaria Mechthild of Bavaria |
| House | House of Wittelsbach |
| Father | Albert IV, Duke of Bavaria |
| Mother | Kunigunde of Austria |
| Religion | Roman Catholicism |
William IV (German: Wilhelm IV; 13 November 1493 – 7 March 1550) was Duke of Bavaria from 1508 to 1550, until 1545 together with his younger brother Louis X, Duke of Bavaria. He was born in Munich to Albert IV and Kunigunde of Austria, a daughter of Emperor Frederick III.