The Kralj class is a class of two fast attack craft

Fast Attack Craft

Fast Attack Craft are small, fast, agile and offensive warships, that are armed with anti-ship missiles, guns or torpedoes. These are usually operated in close proximity to land as they lack both the sea-keeping and all-round defensive capabilities to survive in blue water. The size of the vessel...

, one of which was on order for the SFR Yugoslav Navy and one of which, following the break-up of Yugoslavia, was built for the Croatian Navy. As of 2009 both vessels remain in service.
It is an upgraded version of the Rade Končar missile boat class and is 8.5 meters longer. Kralj Petar Krešimir IV

Kralj Petar Kresimir IV

Kralj Petar Krešimir IV is the first of a 2-strong class of Croatian Kralj class missile boats . It is named after the Croatian king Petar Krešimir IV. It was built in the Kraljevica shipyard in 1991 and commissioned in 1992. It is an upgraded version of the Rade Končar missile boat class and is...

 and its sister ship Kralj Dmitar Zvonimir are the only ships in their class. A potential third ship was under consideration in 1999, but the ship was never commissioned due to budget restraints.

Kralj means "king" in Croatian

Croatian language

Croatian is the collective name for the standard language and dialects spoken by Croats, principally in Croatia, Bosnia and Herzegovina, the Serbian province of Vojvodina and other neighbouring countries...

 - both vessels are named after kings of Croatia.

Units

• RTOP-11 Kralj Petar Krešimir IV
• RTOP-12 Kralj Dmitar Zvonimir