Kniaz’ or knyaz or knez is a Slavic title found in most Slavic languages, denoting a royal nobility rank. It is usually translated into English as either Prince or less commonly as Duke. Today the term knez is still used as the most common translation of "prince" in Croatian and Serbian literature. Another translation is kraljević (Slovene: kraljevič) ("little king" or "kingly"), such as Kraljević Marko, though this term is used to refer to a prince or princess of royal birth, son or daughter of a king. Knez is nowadays a very common surname in some ex-Yugoslavian countries, mostly in Croatia, Montenegro, Serbia and Slovenia.