| Stephen III | |
|---|---|
 Stephen III's seal | |
| King of Hungary and Croatia Contested by Ladislaus II (1162–63), and by Stephen IV (1163–1165) | |
| Reign | 1162–1172 |
| Coronation | June 1162, Székesfehérvár |
| Predecessor | Géza II |
| Successor | Béla III |
| Born | Summer of 1147 |
| Died | 4 March 1172 (aged 24–25) |
| Burial | |
| Spouse | Agnes of Austria |
| Issue Detail |
|
| Dynasty | Árpád dynasty |
| Father | Géza II of Hungary |
| Mother | Euphrosyne of Kiev |
| Religion | Roman Catholic |
Stephen III (Hungarian: III. István, Croatian: Stjepan III.; Slovak: Štefan III.; summer of 1147 – 4 March 1172) was King of Hungary and Croatia between 1162 and 1172. He was crowned king in early June 1162, shortly after the death of his father, Géza II. However, his two uncles, Ladislaus and Stephen, who had joined the court of the Byzantine Empire, challenged his right to the crown. Only six weeks after his coronation, the Byzantine Emperor Manuel I Komnenos launched an expedition against Hungary, forcing the Hungarian lords to accept Ladislaus' rule. Stephen sought refuge in Austria, but returned and seized Pressburg (now Bratislava in Slovakia). Ladislaus, who died on 14 January 1163, was succeeded by Stephen's younger uncle and namesake, Stephen IV, without resistance, but his rule was unpopular. The young Stephen defeated his uncle on 19 June 1163 and expelled him from Hungary.
Stephen IV attempted to regain his throne with Emperor Manuel I's support, but the latter made peace with Stephen III. He agreed to send his younger brother, Béla, to Constantinople and to allow the Byzantines to seize Béla's duchy, which included Croatia, Dalmatia and Sirmium. In an attempt to recapture these territories, Stephen III waged wars against the Byzantine Empire between 1164 and 1167, but could not defeat the Byzantines.
Historians attribute the creation of the "Székesfehérvár laws", the first example of extensive privileges granted to a town in the Kingdom of Hungary, to him. He concluded a concordat with the Holy See in 1169, renouncing the control of the appointment of the prelates. He died childless.