The Millennium Earl is the main antagonist of D-Gray Man. Also known as "The Earl of Millennium", he tricks people using dead relatives and friends into creating Akuma, which become his minions. The Earl is a sorcerer from long ago, and plans to lead the world to its demise. Sometime in the past he formed an alliance with the Noah Family, to whom he is known as "Duke Millennium". The author of D-Gray man, Katsura Hoshino, claims she based The Earl of Millennium off a legendary alchemist/preacher (most likely the Count of St Germain or Nicolas Flamel, though in many ways he also reminiscent of Dorian Gray, possibly referenced in "Dorian Gray man" and thus "D.Gray-Man", as adapted in the film (The League of Extraordinary Gentlemen) whose tale states he may still be alive somewhere.
In appearance, The Millennium Earl resembles a grotesque caricature of a Victorian gentleman -- a rotund figure in a cape and top hat, with an enormous grin that remains fixed even when he is speaking and eating. His eyes are permanently hidden behind a pair of pince-nez spectacles (a type of eyewear that was popular in the 15th, 16th, and 17th centuries.). In the D-Gray man manga, almost every one of the Millennium Earl's lines of dialog ends with a heart symbol; and in the anime, he invariably uses polite and formal Japanese. Throughout the story, he appears to behave in a bipolar fashion. The first is of his personalities is his cheerful, friendly, and happy attitude, which can be compared to that of a loving relative. He is very open and caring with the Noah Family, and is particularly playful and affectionate towards Road. His other personality is one of sheer, sadistic malice, capable of happily toying with people's lives.
The Millennium Earl wears a different hat each time he makes an appearance. In a gag comic in Volume 2 of the manga, he is shown taking off his hat, and having another set of ears. His main form of combat involves the use of his umbrella Lero. The Earl has also shown to have the ability to create massive explosions of dark energy. He is also able to summon a large black sword that is the opposite of Allen's Crown Clown sword. His physical skills are also impressive, since he is able to move at a speed and agility deceiving of his size, and showing enough strength to easily throw around Allen with little effort. The Earl is able to survive direct hits from an Exorcist's Innocence without taking any damage as well, as seen when Lavi engulfed him with a powerful Hi Ban attack, and also when an illusionary Earl was able to survive Allen's Cross Grave attack without taking damage. During his brief fight with Allen Walker, he refers to Allen's new Innocence and states that Allen resembles the "Whiteface Clown who picks on the Auguste Clown". This is a reference to 19th century performing clowns, as that the Whiteface Clow (usually associated with or clad in white) is always the lead in a performance - the clown who throws the pie, while the Auguste Clown (usually associated with or clad in red) is always the fool - the clown who receives the pie in the face. Allen is called the Whiteface Clown by The Earl because of the form his innocence takes, but The Earl may be labeling himself as the Auguste Clown because he's always getting "picked on" by Allen.
The Earl recently traveled to Edo to complete the construction of a new ark to replace the old 'defective' ark. The Earl plays the tune of destruction on a piano while the white ark disappears and a black ark comes out. As the white ark is destroyed, he laughs and cries, even though he said to Road and Lulu Bell that he has a cold. With the black ark complete, the Earl and Noah fly away from Edo. However, due to Allen Walker's interference, the Earl was only able to download 20% of his Akuma producing 'egg'. As a result, the Earl is currently incapable of making any new Akuma, and it is implied that it will take a long time to rebuild the plant. This is the first time in the story when The Earl is seen losing his composure. His face is seen contorted with pure seething rage. However, it is later shown that he is rebuilding his plant and his key concern was what the Black Order might gain from studying the captured egg.
The Earl is shown to have a human form, first seen when he visits Sheryl Kamelot at his estate with Tyki Mikk, although the Earl's face was never shown. It is also the first time in the manga in which he lacks a heart at the end of his speech, and is also devoid of a smile. The Earl was worried about what the Black Order had learned from researching the egg, as it would ruin his plans if they knew the meaning of the Akumas' evolution, leading to "The Heart" knowing about it as well. The Earl also ponders about why he did not kill Allen on the night they have met, mentioning how he has been having dreams since he knew Allen's connection with the 14th Noah. Tyki Mikk mentions the Earl as being "human after all" and that "seeing him like that he did not look like the villain that turn the whole world against him" after watching the Earl (in human form) buy a flower from a poor girl.