first bishop of Kalocsa, who played an instrumental role in the foundation of the Hungarian state and church.

Aseric left the entourage of St. Adalbert (Adalbert, Saint) (Vojtěch), bishop of Prague, to undertake an evangelizing mission in the Magyar lands. He accompanied Adalbert to Rome in 994–996, and on his return he received an invitation from Stephen I, the yet-uncrowned first king of Hungary. As chief counsel to the king, Aseric participated in the organization of the Hungarian church. He was an abbot in Pécsvárad in 999 when Stephen sent him to Pope Sylvester II. This visit to Rome was the pinnacle of his career; while there, according to legend, he obtained archiepiscopal privileges for Esztergom (still the seat of Hungary's Roman Catholic primate). As the papal legate, he brought back the first royal crown (lost some decades later). Following this mission, Stephen appointed him bishop of Kalocsa.