| Wilhelm | |
| Count Palatine of Birkenfeld-Gelnhausen Duke in Bavaria | |
| Spouse: | Countess Palatine Maria Anna of Zweibrücken-Birkenfeld |
| Issue: | Maria Elisabeth, Princess of Neûchatel Duke Pius August |
| House: | House of Wittelsbach |
| Father: | John, Count Palatine of Gelnhausen |
| Mother: | Wildgravine and Rhinegravine Sophie Charlotte of Salm-Dhaun |
| Birth Date: | 10 November 1752 |
| Birth Place: | Gelnhausen, Palatinate-Birkenfeld-Gelnhausen, Holy Roman Empire |
| Death Place: | Landshut or Bamberg, Kingdom of Bavaria |
| Burial Place: | Tegernsee Abbey |
Duke Wilhelm in Bavaria,[1] [2] full German name: Wilhelm, Herzog in Bayern (born 10 November 1752 in Gelnhausen, Palatinate-Birkenfeld-Gelnhausen;[1] [2] died 8 January 1837 in Landshut or Bamberg, Kingdom of Bavaria[1] [2]) was Count Palatine of Birkenfeld-Gelnhausen between 1789 and 1799 and first Duke in Bavaria from 16 February 1799 until his death in 1837. From 17 December 1803 to 20 March 1806, Wilhelm was titled Duke of Berg.
Wilhelm was born on 10 November 1752 in Gelnhausen to John, Count Palatine of Gelnhausen and his wife Wild- and Rhinegravine Sophie Charlotte of Salm-Dhaun.[2] In 1778, Wilhelm became an honorary member of the Bavarian Academy of Sciences and Humanities.[1]
Wilhelm married Countess Palatine Maria Anna of Zweibrücken-Birkenfeld, sister of the first King of Bavaria Maximilian I, daughter of Frederick Michael, Count Palatine of Zweibrücken and his wife Countess Palatine Maria Franziska of Sulzbach, on 30 January 1780 in Mannheim.[2] Wilhelm and Maria Anna had two children:[2]
On 16 February 1799, the head of the House of Wittelsbach Charles Theodore, Elector of Bavaria died. At the time there were two surviving branches of the Wittelsbach family: Zweibrücken (headed by Duke Maximilian Joseph) and Birkenfeld (headed by Count Palatine Wilhelm). Maximilian Joseph inherited Charles Theodor's title of Elector of Bavaria, while Wilhelm was compensated with the title of Duke in Bavaria. The form Duke in Bavaria was selected because in 1506 primogeniture had been established in the House of Wittelsbach resulting in there being only one Duke of Bavaria at any given time.
Wilhelm was interred at the family burial crypt of the Dukes in Bavaria at Tegernsee Abbey.