Stephen the Posthumous was the posthumous son of King Andrew II of Hungary by his third wife, Beatrice d'Este. He was regarded as bastard son of infidelity by his much older half-brothers, including King Béla IV of Hungary, and was not allowed to receive ducal revenues from Hungary to which he would have been entitled as son of a Hungarian king.

Andrew III the Venetian was King of Hungary and Croatia between 1290 and 1301. His father, Stephen the Posthumous, was the posthumous son of Andrew II of Hungary although Stephen's older half brothers considered him a bastard. Andrew grew up in Venice, and first arrived in Hungary upon the invitation of a rebellious baron, Ivan Kőszegi, in 1278. Kőszegi tried to play Andrew off against Ladislaus IV of Hungary, but the conspiracy collapsed and Andrew returned to Venice.