Noble

Noble (貴族) is a state-privileged status which is generally hereditary. Titles of nobility are usually associated with present or former monarchies. The term originally referred to those who were "known" or "notable" and was applied to the highest social class in pre-modern societies.

Nobles in One Piece
Nobles are not to be confused with World Nobles as nobles are people restricted to their respective kingdoms while the World Nobles are people who were descendants from the Twenty Kingdoms and live only in Mariejois whose noble status is universal.

A majority of the nobles shown in the series have been portrayed as heartless. In particular, the nobles from Sabaody Archipelago, who were afraid of getting infected after Hatchan was shot and remorseless at the fact he was shot, as well as the Goa Kingdom nobles deciding to have Gray Terminal burned and shoot the people living there who tried to escape to make the kingdom beautiful for the visiting World Noble, Saint Jalmack, in hopes to be given a step up in their noble status. They also believe that the "commoners" are fools for reasons outside of their control, one key statement where a father told his daughter they were trash and fools because they were not born as nobles, claiming they were stupid for not "choosing to be born noble". All nobles have been shown to be very cowardly, where despite their fearsome reputation they often cower to any threat of physical violence. They also seem to believe people are only interested in money, often bribing or suggesting money as a form of defense and if that doesn't work suggest the consequences that harming them would cause, and will believe the person is insane if they do not accept the money or threat. In other words, they have no idea how the real world works outside their own petty and selfish reasons. Hody Jones even believes that by being a king, one has the right to be selfish. A noble becomes a true noble at age eighteen.

Currently, some of the few people to whom this has not extended would be the rulers of the Kingdom of Alabasta, who truly care deeply for their people despite the differences in status and fight to protect them, going as far as self-sacrifice as well as considering blowing up their own castle. Wapol's Father, and later his successor Dalton, also only cared for the well-being of their people, and are loved by the kingdom in return. Thalassa Lucas, a responsible king, also shows no arrogance. Sabo, who was deeply disgusted by the way nobles act, wished to have his status as one revoked, another prime representation of a benevolent nobility. This also extends to the depths of Fishman Island, in which Neptune, king of the island, personally came to thank the Straw Hat Pirates for their actions, protecting his servants at the cost of harm towards himself, and considers Hody's ideals of attacking the citizens as selfish. This also extends to his children and his late wife, who hope to use their powers to migrate their species to the surface and once and for all remove the cycle of hate that has occured between humans and fishmen.

Trivia

 * Currently, Sabo is the only noble to be ashamed of his status.
 * Saru is the only known animal with noble status.
 * Hody Jones is so far the only character to give himself the noble title of King, though he failed to officially achieve it before being defeated by Monkey D. Luffy.
 * While several characters such as the Gorgon Sisters, Nyon and the Goldfish Princess are considered to be royalty, they cannot be nobles, as they do not belong in any World Government-sanctioned kingdoms.