* AdaptationOverdosed: ''GTO'' has a 43-episode anime adaptation, a live-action film, and no fewer than 4 live-action TV series. And then there's the spinoff ''GTO: 14 Days in Shonan'' and the sequel ''GTO: Paradise Lost''. Its predecessor ''Manga/GTOTheEarlyYears'' also has several live-action adaptations and an {{OVA}} series.
* CreatorBacklash: A panel in 2010 revealed that Kunio's primary English voice, Creator/TonyOliver, didn’t care much for the character due to his Oedipus complex.
* TheDanza: Akane Fujita's boyfriend Hideo is voiced by Creator/HideoIshikawa.
* DirectedByCastMember: The French dub of the anime was directed by Éric Peter, who also provided additional voices.
* IronyAsSheIsCast: In the 1998 live-action, Kirari (the singer of the anime's first ending theme) plays Nanako, who shows how HollywoodToneDeaf she is when Onizuka considers entering her in an idol contest.
* KeepCirculatingTheTapes: ''GTO'' has been out of print since Creator/{{Tokyopop}} stopped publishing manga, so the only way to read it is to buy a used copy online or read the scans. Also, the 1998 live-action survives on various websites including [=YouTube=].
* LongRunners: ''GTO'' is an interesting case. The manga itself only lasted 5 years (1997-2002) with 207 chapters, but it continued the story begun with ''Manga/GTOTheEarlyYears'' (1990-96), which had 267 chapters (plus the 10-chapter OriginsEpisode ''Manga/BadCompany''). Tooru Fujisawa then took a break for a few years, before returning to Onizuka's story with ''GTO: 14 Days in Shonan'' (2009-11, 77 chapters) and ''GTO: Paradise Lost'' (2014-present, currently at 144 chapters). This is excluding the non-Onizuka-centric stories ''GT-R: Great Transporter Ryuji'' (2012), ''Manga/InoHeadGargoyle'' (2012-2014), and ''Shonan Seven'' (2014-2019), which take place in the same universe. Therefore, the "GTO-verse" has run for 24 non-consecutive years over 8 different series (5 of them about Onizuka himself, over 21 years).
* TheOtherDarrin: Where do we begin with this one? On the Japanese side, when the ''GTO'' anime was created, none of the actors from the original Shonan Junai-gumi O[=V=]As returned to their parts. Granted, there weren't many returning characters from the latter besides Ryuji and Onizuka himself, but still. The only returning actors in ''GTO'' were Creator/ShinichiroMiki, Creator/HisaoEgawa, Creator/YasunoriMatsumoto, and Creator/YuriShiratori in completely unrelated parts.
** Creator/WataruTakagi replaced Creator/IsseiFutamata as Onizuka.
** Creator/IsshinChiba replaced Creator/HideyukiHori as Ryuji.
** Creator/KazukiYao replaced Creator/KenNarita as Saejima.
** Creator/KaeAraki replaced Creator/MegumiHayashibara as Nagisa for her brief cameo.
** Plus Creator/KayaMatsutani replaced Creator/MichikoNeya as [[SameCharacterButDifferent Nao Kadena]].
** Also, in the ''GTO'' anime alone, minor supporting teacher Koji Sannomaru was voiced by Creator/TsutomuTsuji for his first couple of appearances before being replaced for the remainder of the show by Creator/HirohikoKakegawa.
** On the English side of things, the ''GTO'' anime had many inconsistencies with its supporting cast. Most of the children of Class 3-4 were subject to recasting depending on whether some actors were available or not to record. The only students who didn't fall victim to this at some point were Fujiyoshi, Kusano, Tomoko, and Urumi.
** In particular, Creator/KirkThornton was for whatever reason unavailable to record for volume 4, so his roles were filled in by Creator/DougErholtz (Yoshikawa) and Creator/DaveWittenberg (Kikuchi, Ryuji, and Sannomaru). Kirk would return for the remainder of the series with volume 5.
** Kunio was first voiced by Creator/BrycePapenbrook in episode 4 (alongside [[Creator/BobPapenbrook his father]] who voiced Uchiyamada and some extras) before being replaced by Creator/TonyOliver for the rest of the run. Bryce was a high school student at the time of recording and couldn't devote any more time to the series.
** Speaking of the fourth episode, another oddity was that Anko and Miyabi's actresses, Creator/DorothyEliasFahn and Creator/WendeeLee respectfully, originally had their roles reversed with Wendee even voicing Anko in the preview for the next episode. After this, Dorothy stayed with Anko for the remainder of the show except in volume 3 when she wasn't available, so Creator/CindyRobinson voiced the character for episode 14. Wendee would continue on as Miyabi from episode 7 to the series' end.
** That was nothing compared to their [[GirlPosse Girl Posses]], who never had consistent actresses in the dub. Poor Saeko had a grand total of '''FIVE''' different actresses voicing her across all her appearances! First Creator/ChristineRuprecht voiced her in episode 7, next Creator/PhileceSampler in episode 9, then Creator/DebbieRothstein was settled on as the de facto voice (with Wendee Lee filling in for volume 4). However, Debbie did not return for volume 7 and onwards, so Cindy Robinson finished up for Saeko's remaining speaking parts. Chikako faired far better in comparison; she was mainly voiced by Sampler with the sole exception of episode 16, where Creator/KateHiggins filled in.
** As for Anko's lackeys, Mayuko was voiced by Debbie Rothstein for volume 2 but way down the line in volumes 9 and 10, because of the above mentioned with Saeko, was replaced by Kate Higgins. Naoko, on the other hand, had four different actresses. Cindy Robinson voiced her in volume 2, but since she was now filling in as Anko for that volume, she didn't return as Naoko and was replaced by Christine Ruprecht. Since Cindy was already voicing Saeko for the Okinawa episodes, Naoko was recast a third time with an uncredited Creator/LaraJillMiller on volume 9. Miller did not return for the final volume so Naoko had to be recast yet again, this time with Creator/KarenStrassman.
** Two members of the Holy Forest staff also fell victim to this in episode 3, with Creator/BradRowen and Wendee Lee voicing Sakurada and Kochatani, the latter was especially noticeable since the male teacher was voiced by a woman. Steve Blum, already voicing Onizuka and Fujiyoshi, would take over as Kochatani for the rest of his speaking appearances while Tony Oliver would voice Sakurada in episode 6 only before handing the role to Dave Wittenberg for the rest of the run.
** Saejima was voiced by Creator/RichardEpcar (already Fukuroda) for his first two appearances but was replaced by Creator/SkipStellrecht for his remaining three outings.
** Finally, there's Uchiyamada's wife and daughter, Ryoko and Yoshiko. Originally, they were played by Debbie Rothstein (Uchiyamada's English voice's [[RealLifeRelative actual wife]]) and Dorothy Elias-Fahn in volume 1. In the second volume, however, while Dorothy was still Yoshiko, Wendee Lee had taken over as Ryoko. It was strange considering that Debbie was in volume 2 voicing Mayuko and Mrs. Uehara. Later still in volume 6, where the vice-principal got ADayInTheLimelight, both Uchiyamada women were recast again with Kate Higgins voicing Yoshiko and Philece Sampler providing Ryoko's voice. It's, again, strange since Dorothy was also in the volume voicing Nao.
** On a minor note, Tomoko's father was voiced by Dave Wittenberg in episode 9 but got replaced by Tony Oliver in the penultimate episode.
* PlayingAgainstType:
** Creator/JunkoNoda, who's usually cast in ActionGirl or CoolBigSis roles, plays the AlphaBitch Miyabi Aizawa.
** Creator/ToruFuruya, who's best known for more heroic roles such as [[{{Franchise/Gundam}} Amuro Ray]] or [[{{Franchise/SailorMoon}} Tuxedo Mask]], is playing the creepy StalkerWithACrush Teshigawara.
* RealLifeRelative: This is only the case in Episode 4's English dub, with Creator/BobPapenbrook as Uchiyamada and his son Creator/BrycePapenbrook as Murai. After this episode, however, the dub voice of Murai was taken over by Creator/TonyOliver.
* RomanceOnTheSet: The live-action actors of Onizuka and Fuyutsuki (Takashi Sorimachi and Nanako Matsushima) ended up together in RealLife.
* SequelGap: ''GTO'' finished in 2002, and didn't get a sequel until 2009 with ''GTO: 14 Days in Shonan''. This is probably because Creator/TooruFujisawa wanted to focus on his other series, like ''Manga/RoseHipRose'', ''Manga/KamenTeacher'', and ''Manga/AnimalJoe''.
* StarMakingRole: Onizuka was Creator/WataruTakagi's breakout role as the main character.
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