Will of D.

In the One Piece fictional universe, few characters have the middle initial "D". This mysterious middle initial has been called "the Will of the D" (Dの意志, D no Ishi) or "D's will" by several characters in One Piece. Some translations mistakenly refer to it as "Gol D's will" in reference to Gol D. Roger, the late pirate king. The English dub by 4Kids choses to refer to the D as the "Gol D.'s will", while the FUNimation dub refers to it simply as "the Spirit of Gol D." both deriving from a mistranslation of the original Japanese text. In the recap supplement Grand Line Times, they were referred to those who carry it as "The men of D."

What is the D?
Inherited will, the swelling of the changing times, And the dreams of people. These are things that cannot be stopped. As long as people seek the answer to freedom, these will never stop!

One Piece, second intro and words heard in Loguetown.

It is not clear what the significance of the shared middle initial is, but it appears that all share a similar faith in their own (and others') dreams and/or destiny. Furthermore, they seem to be able to withstand incredible punishment in battle and only surrender to death when they know there truly is no way of avoiding it.

In Oda's SBS questions and answers corner, he was asked what the D in Luffy's name stood for. Oda just replied to read it as a D for now and that he would reveal the truth behind it in time. This was the first time Luffy's 'D' was brought up, as well as Oda's first hint towards a bigger mystery.

In the storyline, Dr. Kureha is the first to mention The Will Of D and it was revealed by her that Gold Roger's (the late pirate king) true name was Gol D. Roger. She tells Dalton that Chopper has joined up with a very dangerous man. So it still lives... The will of D.

- Dr. Kureha speaks to Dalton about Luffy Recently, Robin tried to ask Silvers Rayleigh about the significance of The Will Of D at the same time as mentioning the Void Century. While he did not reply on what the D stood for, Silvers stated that they (The Jolly Roger Pirates) discovered the details on the Void Century, but when he offers to tell her, she turns down his information. Robin agrees to discover the truth herself.

Family
One clue about those who carry the "D" was left by Jaguar D. Saul who specifically said that while he didn't know the meaning of the initial, he did know everyone in his family carried it in their names.

So far, its seems that the Ds all may indeed be related to each other. Luffy does have a grandfather, Vice-Admiral Garp, whose full name is Monkey D. Garp. Luffy is also the son of the revolutionary Monkey D. Dragon. In addition, Luffy's adoptive brother, Portgas D. Ace, has also been revealed to be blood related to Gol D. Roger and Portgas D. Rouge.

Known Family Names

 * Monkey
 * Gol
 * Marshall
 * Jaguar
 * Portgas

The Concept of Death
An odd trait of the D's is related to death. Often they are seen laughing or smiling greatly when they are about to die, as if they seem to accept their death when they cannot escape it and display no apparent fear toward death. The reactions of many characters who witness this is often shock or disbelief because it is hard to imagine anyone not being afraid of dying at all. So far this strange habit has been shown 6 times:
 * Monkey D. Luffy was laughing as his first boat sunk into a whirlpool.
 * Witnesses claim Gol D. Roger died smiling during his execution.
 * 22 years later one of those witnesses, Smoker, witnessed Luffy smiling in the same manner as Gol D. Roger when Buggy was about to kill him.
 * Nico Robin also witnessed Saul laughing and smiling as he was frozen by Aokiji.
 * Portgas D. Rouge is seen smiling during the naming of Ace right before death via. childbirth.
 * Portgas D. Ace was smiling after he thanked everyone for loving him right before his death.

There was almost a seventh instance which was the duel between Ace and Blackbeard, in which both Ace and Blackbeard smile before their final attack against each other. Ace did not die and was only defeated and sent to Impel Down but both probably thought they would either win or die.

Their Knowledge on Themselves
The biggest mystery with the D's is that those who carry the D. themselves do not know fully what it means either. Jaguar D. Saul displayed an absence of knowledge on the subject of the D. when Nico Robin asked him what it meant. When she asked Monkey D. Luffy why those that carry the D. fight, he was also completely clueless as to what she was talking about. Though it seems that the Marines are somewhat aware of the D's as Sengoku showed interest in Ace because of it.

Alive
At 17 Luffy is the youngest pictured D. carrier thus far in the story. Monkey D. Garp appears to be the oldest known living carrier of the D.


 * Monkey D. Luffy: (Known as "Straw Hat Luffy"): Captain of the Straw Hat Pirates
 * Monkey D. Dragon: (Known as "Revolutionary Dragon"): Leader of the Revolutionaries
 * Monkey D. Garp (Known as "Garp the Fist"): Marine Vice Admiral
 * Marshall D. Teach (Known as "Blackbeard"): Former subordinate of the Whitebeard Pirates second division, Captain of the Blackbeard Pirates, Shichibukai member

Deceased
In the present storyline, Roger has been dead for 22 years. Saul has been dead for twenty years. Saul was a giant, making him the only apparent non-human "man of D" in the storyline. As a giant, his age may have been anywhere up to 300 years (the normal lifespan of a giant). Rouge has been dead for 20 years, and is the only known female to carry the D. in her name.
 * Gol D. Roger (Known as "Pirate King"): Captain of the Jolly Roger Pirates; Turned himself in for execution after being diagnosed with a fatal illness.
 * Jaguar D. Saul: Former Marine Vice Admiral; Killed by Vice Admiral Kuzan for betraying the Marines.
 * Portgas D. Rouge: To date the only known female bearer of the "D", Gol D. Roger's lover and Portgas D. Ace's mother; Died in childbirth after sustaining Ace in her womb for twenty months.
 * Portgas D. Ace: (Known as "Fire-Fist Ace"): Former Captain of the Spade Pirates, Commander of the second division of the Whitebeard Pirates; Killed by Admiral Akainu while defending Luffy.

Translation and Dub Issues
The English translations that use of "Gold D's spirit" or "Gol D.'s Will" instead of "Will of D" in Dr. Kureha talk to Dalton can be considered an error. While Gold Roger is spoken of in the previous lines of text, Kureha made no mentioned of Roger in that particular line of text in the original Japanese manga and anime.

Trivia

 * A few of the characters with the D. have shown to be narcoletic, such as: Garp, Ace and Luffy. So far it has yet been stated if this is a trait to the Will of D. But this could also be attributed to the care free nature.