* ActingForTwo: Lavi and the Millennium Earl were both originally voiced by Creator/JasonLiebrecht. When he was injured due to a motorcycle accident, Creator/ToddHaberkorn temporarily filled in for Earl during his appearances in episodes 27-39 while also playing Allen and Creator/ChrisPatton filled in for Lavi.
* CrossDressingVoices: Allen's Japanese voice actor in the first series is Creator/SanaeKobayashi. In English, it's only played straight with Young Allen, who, in the flashbacks, is voiced by Creator/LuciChristian, who also plays Lenalee. It is averted in the present, where Allen is played by Creator/ToddHaberkorn.
** {{Averted}} now in the Japanese version of Hallow, since Allen is now voiced by Creator/AyumuMurase.
* DisownedAdaptation: During a 2016 interview for ''Hallow'', Katsura Hoshino admitted that the first season of the anime was a mess due to TMS Entertainment changing several elements of her original manga and addition of filler sequences. TMS initially offered to produce ''Hallow'' and release it with the manga after its hiatus. Hoshino unsurprisingly declined the offer, but TMS would eventually convince Hoshino to accept their offer. Hoshino served as a supervisor for ''Hallow'' to help make the series stay closer to her manga and to make up for what TMS had done the first anime.
* DoingItForTheArt: At this point, after years of hiatuses and with a chapter every 3 months, Hoshino is no longer concerned by cancellation (the Jump SQ Crown mostly publishes one-shots anyway) and can pretty much do whatever she wants with her series. It's very unlikely that the latest volumes would have veered off so much from a traditional shonen formula if the series had stayed weekly.
* IKnewIt: [[spoiler: The Earl has horns]]. Doubly so for those who read ''Zone'', the oneshot that provided the inspiration for the entire series.
** On a meta example, there were fans that guessed that the 2016 series would be part of Creator/FUNimation's summer simulcast season, despite not releasing the series for five years because of legal issues between them and Dentsu. Turns out they were right.
*** And there were also people thinking that licensing the 2016 series would lead to [=FUNimation=] licensing the second half of the 2006 series. On June 30, 2016, [=FUNimation=] announced that they acquired the rest of the 2006 ''D. Gray Man'' series.
* KeepCirculatingTheTapes: On March 1, 2017, the home media release of ''Hallow'' was cancelled due to various circumstances. Fortunately, the episodes are available online.
* NoExportForYou: Episodes 52-103 of the 2006 series was originally not released in North America since 2011 due to [[ScrewedByTheLawyers legal issues with Dentsu]]. It would take ''five years'' for [=FUNimation=] to finally license episodes 52-103 in 2016, along with the 2016 continuation, ''Hallow'', once the legal issues were sorted out.
* OldShame: Katsura Hoshino lamented that TMS Entertainment would never be able to adapt it into an anime again after the first season. Hoshino would eventually become the supervisor for ''Hallow'' at the insistence of TMS after she repeatedly declined their offers to adapt ''D. Gray-Man'' into an anime again.
* TheOtherDarrin:
** In the 2016 series, most of the Japanese cast have new voices.
** In the English dub, when Creator/JasonLiebrecht was injured in a motorcycle accident, both of his roles, Lavi and Millennium Earl, were temporarily recast with Creator/ChrisPatton and Creator/ToddHaberkorn (Allen's voice) respectively during their appearances in episodes 27-39.
** Hallow's dub has Creator/IanSinclair taking over for Creator/TravisWillingham as Kanda due to the latter being mostly in union-only projects after moving to Los Angeles. Froi will also need replacing should he appear, as his original actor Jerry Russell died a few years before Funimation picked up the rest of the series.
* RelationshipVoiceActor: The English dub has several.
** [[Creator/ToddHaberkorn Allen]] and [[Creator/CheramiLeigh Road]] are also [[Manga/SoulEater Death the Kid and Patty Thompson]], [[Manga/DaimidalerTheSoundRobot Shouma and Kiriko]], [[Manga/FairyTail Natsu and Lucy]], and, in a darker example, [[LightNovel/SwordArtOnline Sugou[=/=]Oberon and Asuna]].
** [[Creator/ToddHaberkorn Allen]] and [[Creator/LuciChristian Lenalee]] are the teen and kid versions of [[Manga/FairyTail Natsu]], respectively.
** [[Creator/ToddHaberkorn Allen]] and [[Creator/TravisWillingham Yu Kanda]] (in the first 51 episodes) are [[VideoGame/FireEmblemAwakening Male Morgan and Lon'qu and Brady]].
** In the Japanese version, [[Creator/KenichiSuzumura Lavi]] and [[Creator/TakahiroSakurai Yu Kanda]] are voiced by best friends Suzumura Kenichi and Takahiro Sakurai, who also were the voices for [[VideoGame/FinalFantasyVII Zack and Cloud]], [[Manga/ZombieLoan Chika and Shito]], [[Manga/SeraphOfTheEnd Crowley and Ferid]] and many more.
* ScrewedByTheLawyers: Eventually {{subverted|Trope}}. Creator/{{Funimation}} began arranging plans to release the remaining 52 episodes of the 2006 series in North America after releasing the first 51 episodes. However, the release got locked away in 2011 thanks to Dentsu asking [=Funimation=] for more money than the company was willing to afford. In June 2016, [=Funimation=] announced that it had licensed ''Hallow'' as part of the 2016 Summer Simulcast season, as well as the second half of the 2006 series a week later.
* {{Uncanceled}}: The series got a sequel almost a decade after the original ended.
** The English release was haulted after 51 episodes were released in 2009-2010 due to legal issues with Dentsu, only for [=FUNimation=] to finally license 52-103 in 2016 along with ''Hallow'' after those issues were resolved.
* WhatCouldHaveBeen:
** Creator/ToddHaberkorn, also the director of the first half of the 2006 series, knew about the Black Order members being British, and contemplated putting those accents on them. He decided against it because the test recordings made Allen sound harsher and less appealing, and their natural accents would be easier on the actors (this was when they had initially planned to dub the show to the end, like a long-runner).
** Lavi was originally intended to be main character for the series called "BOOK-MAN", a project which never reached beyond the planning stages. Still, the author wanted to use him and Bookman so they made it into ''D.Gray-man'' as side characters instead.
* TheWikiRule: Has a wiki [[http://dgrayman.wikia.com/wiki/D.Gray-man_Encyclopedia here]].
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