Ladislaus III of Hungary

Ladislaus III (Hungarian: III. László, Croatian: Ladislav III., Slovak: Ladislav III.; c. 1200 – 7 May 1205) was King of Hungary and Croatia between 1204 and 1205. He was the only child of King Emeric. Ladislaus was crowned king upon the orders of his ill father, who wanted to secure his infant son's succession. The dying king made his brother, Andrew, regent for the period of Ladislaus's minority. However, Duke Andrew ignored the child's interests. As a result, Ladislaus's mother, Constance of Aragon, fled to Austria, taking Ladislaus with her. Ladislaus died unexpectedly in Vienna.

Source: Wikipedia — https://en.wikipedia.org/wiki/Ladislaus_III_of_Hungary