Princess

A Princess is a female heir to the throne. She is usually a daughter of a King and/or Queen and is in a position where she legitimately could inherit her country's throne.

Overview
A princess is a female born into a royal family and is the daughter of the sovereign King or Prince. A woman who marries a Prince may also be granted the courtesy title of "Princess", though it is worth noting that a man who marries a Princess in contrast can never earn the title of "Prince".

While male heirs are considered a "heir apparent" (also known as "Crown Prince"), females on the other hand are normally born as "heir presumptive". This is because male heirs take preference over female heirs, since if a female marries into another family, that family then has a claim to the royal throne making the only way for a safe, unchallenged line of succession is by producing a male heir. She does not become "heir apparent" (also referred to as "Crown Princess") unless there are no male heirs in front of her in the line of succession to the throne. A princess therefore is ranked lower then male heirs.

While a Prince's duties normally focuses on his possibility of one day becoming King (military, political, etc) and therefore he plays a more active role in the royal court. In contrast, a Princesses duties are normally focused on more passive roles, especially if she is a "heir presumptive".

A princess who does manage to succeed to power normally is granted the title of "Queen regnant".

In One Piece
Currently, very few princesses made an appearance in One Piece.

The most notable princess is Nefertari Vivi of Alabasta who traveled with the Straw Hat Pirates during the Alabasta Saga. Vivi does not follow the real world tradition of a princess in many ways, in the sense she can be more like a commoner at times than royalty.

The second prominent princess is Shirahoshi of Ryugu Kingdom, who is also considered to be the Mermaid Princess, a legendary figure who can summon Sea Kings.

Mansherry is the princess of Tontatta Kingdom, and accordingly, she is spoiled, cruel and selfish, though still a comrade for her people to want to save her.

Rebecca is the lost princess of the Riku royal family of Dressrosa that was overthrown by Doflamingo and is now forced to be a gladiator; her mother and aunt were the first and second crown princesses of the country before Doflamingo overthrew them.

Hatchan met the Goldfish Princess in his seafloor stroll.

Current Princesses

 * Nefertari Vivi is the princess of the Alabasta Kingdom.
 * Goldfish Princess is the princess of the Goldfish Kingdom.
 * Shirahoshi is the princess of the Ryugu Kingdom.
 * Mansherry is the princess of the Tontatta Kingdom.

Former Princesses

 * The previous Poseidon, who was the first known "Mermaid Princess" of Ryugu Kingdom.
 * Scarlett is the daughter of king Riku Dold III and the first crown princess of Dressrosa before her assumed and actual demise at the hands of Diamante.
 * Viola is the daughter of king Riku Dold III and the second crown princess of Dressrosa before swearing her loyalty to the Donquixote Pirates.
 * Rebecca is the lost princess of the fallen Riku royal family of Dressrosa.

Princess as an Epithet

 * Perona: Ghost Princess
 * Boa Hancock: Snake Princess
 * Shirahoshi: Mermaid Princess
 * Rebecca: Phantom Princess