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 he legitimately could inherit his country's throne.

Current Princes

 * Fukaboshi is the crown prince of the Ryugu Kingdom, and successor to the throne.
 * Ryuboshi is the second prince of the Ryugu Kingdom.
 * Manboshi is the third of the Ryugu Kingdom.
 * Vinsmoke Ichiji is the first prince of the Germa Kingdom.
 * Vinsmoke Niji is the second prince of the Germa Kingdom.
 * Sanji is the third prince of the Germa Kingdom (although he renounced his royal status many years ago).
 * Vinsmoke Yonji is the fourth prince of the Germa Kingdom.

Former Princes

 * Wapol was the spoiled prince of the Drum Kingdom before his father's death, which allowed him to ascend the throne.
 * Bellett was the prince of an unnamed kingdom who was imprisoned in Impel Down, until his kingdom fell apart.

Non-canon Princes

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

Prince as an Epithet/Alias

 * Sanji: Mr. Prince (Mr.プリンス)
 * Cavendish: Pirate Prince (海賊貴公子)