The Clan of Ostoja (old Polish: Ostoya) was a powerful group of knights and lords in late-medieval Europe. The clan encompassed families in the Polish–Lithuanian Commonwealth (including present-day Belarus and Ukraine), Hungary and Upper Hungary (now Slovakia), Transylvania, and Prussia. The clan crest is the Ostoja coat of arms, and the battle cry is Ostoja ("Mainstay") or Hostoja ("Prevail"). The clan, of Alan origin, adopted the Royal-Sarmatian tamga draco (dragon) emblem.