Stibor of Stiboricz of Ostoja (also written in English as Scibor or Czibor; Polish: Ścibor ze Ściborzyc, Hungarian: Stiborici Stibor, Romanian: Știbor de Știborici, Slovak: Stibor zo Stiboríc; c. 1348 – February 1414) was an aristocrat of Polish origin in the Kingdom of Hungary. He was a close friend of King Sigismund of Hungary who appointed him to several offices during his reign. For instance, between 1395 and 1401, then from 1409 to 1414 he was the Voivode of Transylvania (now in Romania). Stibor styled himself "Lord of the whole Vág", referring to his properties along the 409-km-long river (in present-day Slovakia) where 15 of his 31 castles were situated.