Prince

A Prince is a male heir to the throne. He is usually a son of a King and/or Queen and is in a position where she legitimately could inherit her country's throne.

Known Queens

 * Bellett was the prince of an unnamed kingdom who was imprisoned in Impel Down.
 * Fukaboshi, Ryuboshi, and Manboshi are the princes of the Ryugu Kingdom.

Non-canon

 * Musshuru was the prince of the Drum Kingdom in the 9th movie.