Boleslaus (, ; died 1212 or 1213) was a prelate in the Kingdom of Hungary at the turn of the 12th and 13th centuries. He was Bishop of Vác between 1193 and 1212. He supported Duke Andrew during the Duke's conflict with his brother, King Emeric of Hungary. Early life Boleslaus was born in the 1130s into a prominent noble family, but his parentage and origin is unknown. He had a brother (or at least, relative; frater) Elvin, also a prelate, who served as Bishop of Várad (present-day Oradea, Romania) from 1189 to 1200. Based on the geographical location of their landholdings, historian Vince Bunyitay considered that both of them belonged to the gens (clan) Becsegergely. Other historians – including Samu Borovszky and Ferenc Chobot – accepted his interpretation. Boleslaus' godfather was the reigning monarch, Béla II of Hungary (r. 1131–1141) at his birth, according to later documents. Boleslaus was granted the royal estate of Lelesz (present-day Leles, Slovakia) as a christening gift by Béla II (before that Lelesz belonged to the surrounding estates of Zemplén Castle). By the reign of Stephen III of Hungary (r. 1162–1172), Boleslaus was elevated into the position of provost of the collegiate chapter of Buda in the 1160s. Possibly he is identical with that provost "Boleslav" (with unspecified see), who appeared in a contemporary document in 1162. Stephen III sent him to draft and determine the borders of the Szentjobb Abbey (present-day Sâniob in Romania) around 1169. Boleslaus himself recorded the description in a charter, which implies that he was also a member of the royal chapel during that time. It is possible that Boleslaus is identical with that unnamed provost of Buda, who was mentioned in a royal charter of 1178 with dubious authenticity, which only preserved the first letter of his name ("B"), but this may also apply to his successor Barnabas. Boleslaus participated in the Hungarian military campaign to the Principality of Halych in 1188, when Béla III of Hungary (r. 1172–1196) invaded the principality and installed his son Andrew as Prince of Halych. For his participation, Béla III granted the king's share (one third part) of the port duty of Szolnok along the river Tisza to Boleslaus, who also acquired the village of Kabala with the approval of the monarch. Later, Boleslaus handed over this land to his nephew, Marhard in exchange for his portion at Lelesz. Boleslaus also owned