William of Celje | |
|---|---|
 William's coat of arms | |
| Count of Celje | |
| Reign | 1385 – 1392 |
| Predecessor | Hermann I of Celje |
| Successor | Hermann II of Celje |
| Noble family | House of Celje |
| Spouse(s) | Anna of Poland |
| Issue | Anna of Celje |
| Father | Ulrich I |
| Mother | Aldelaide of Ortenburg |
William of Celje (German: Wilhelm von Cilli, Slovene: Viljem Celjski; c. 1361 – 19 August 1392), also William of Cilli, Count of Celje, was a Styrian nobleman who was married to Anna of Poland, daughter of the Polish king Casimir the Great. He was the co-ruler of the House of Celje together with his uncle Hermann I until 1385 and then with his cousin Hermann II until his death. William's only daughter, Anna of Celje, married the Polish King Władysław II Jagiełło in order to strengthen his claim to the Polish throne.