Their designs, inspired by the oni of Japanese folklore, Ultraman, Iczer-One, Devilman, and other sources, caused problems during the production of the animated series but have received a positive reception from critics and audiences and have been used for merchandise.
Hideaki Anno, director and principal screenwriter of Neon Genesis Evangelion, initially sought to create what he called "a simple work featuring robots".
Iczer One, starting from the image of a girl in a capsule-shaped cockpit full of liquid – prototypes of the Eva-00 pilot Rei Ayanami and the Entry Plug – but without having a precise plot in mind.
Other images became the basis of Evangelion, such as skyscrapers emerging from the top of mountains, robots carrying batteries, people dragging large cables, and a city in the peaks named Tokyo-2 in Nagano Prefecture.
While watching a documentary on the Japanese TV station NHK named The Fantastic Microcosm of the Human Body: Brain and Soul (驚異の小宇宙 人体II 脳と心, Kyōi no shōuchū jintai: nō to kokoro) the artist learned of the existence of A10 nerves.
Sadamoto also compared the Nerv with the Solo Ship from Space Runaway Ideon, whose crew faces hostile aliens of the Buff Clan and other humans, with mecha that go out of control and communicate only with children.
[6] In a preliminary draft during the early planning stages of the animated series, staff suggested the existence of two ancient prehistoric civilizations that appeared on Earth before humans, both of whom were equipped with advanced technologies.
The Second Ancestral Race would have created a weapon known as the Longinus Spear in an attempt to defeat the humanoids, scattering warriors named Angels in a state of hibernation around the globe as a countermeasure in case anyone tried to reactivate the Evangelions.
[10] One of the preliminary drafts of the twenty-fourth episode, written by screenwriter Akio Satsukawa, also introduced a prototype mini Evangelion,[11] a five-meter mecha named αーTYPEーEVA000, also known as α Eva.
[23] Cannibalism, according to Yūichirō Oguro, curator of extra contents of Evangelion's home video editions, would negatively depict the act of eating meat and could also be influenced by Anno's personal experience, who has been vegetarian since childhood and had already transposed this detail of his life in his fictional works.
[38] To give the Eva's cockpit the image of a mother's womb, Anno asked Shiro Sagisu, who was responsible for the series' soundtrack, to compose a melody that would accentuate the feeling of nostalgia.
In a section of Nerv's headquarters called Terminal Dogma, there are skeletons of bodies believed to be precursors to the Eva-00, or the remains of failed experiments that occurred during its creation; the experimental models have two or more optical sensors[48][49] and a visible spine.
[77] The pilot of an Evangelion unit, designated by the English term Child, is housed in a cylindrical capsule called an Entry Plug, which is inserted into the area corresponding to the humanoid's spine, at the cervical vertebrae.
[113] Unit 01 (初号機, Shogōki), or Test Type,[114] is the experimental model of the Evangelion series[115] and the second specimen to be built in the Nerv headquarters, studied under the direct supervision of Dr. Yui Ikari.
[131][132] Although the conception and construction of the machine took place in Japan,[133] the assembly and activation experiments, as well as the training of its pilot, the Second Child Asuka Langley Soryu,[134] are performed in Germany.
[167] Once it arrives in Japan, preparations begin for its activation experiment to take place in the city of Matsushiro, Nagano Prefecture, where Nerv's second experimentation site is located.
[183] The Eva Series (エヴァシリーズ, Evashirīzu) includes units 05 through 13, built at various Nerv branches at the behest of the Seele organization to carry out a plan known as the Human Instrumentality Project.
[244] In the theme song, A Cruel Angel's Thesis, Unit 01 is depicted with twelve wings of light, referring to the iconography of Satan[245] and taking a cue from the manga Devilman.
[247] The scene in which Eva-01 is first introduced in the first episode has also been compared to Tadao Nagahama's Combattler V,[248][249] while for Carl Gustav Horn, editor of the North American edition of the manga, the Eva units can be "possibly connected to the legend of the Golem, a giant artificial man which does its creator's bidding".
[259] The book Evangelion Glossary (エヴァンゲリオン用語事典, Evangerion Yougo Jiten) by Yahata Shoten noted how in Craig Thomas' Firefox the idea of a fighter pilot's thought-guided weapon capable of controlling missile launches using brain waves is presented.
[263] Japanese architect and academic Tomoko Sakamoto also noted how images similar to those in 2001: A Space Odyssey (1968) appear in the Entry Plug during the activation of the connection between Eva and pilot.
[306] A similar result was recorded in 2016, when the website Charapedia asked its users which machine that appeared in a Japanese animation series they wished to use or pilot; the Eva-01 was the second most popular answer, with almost four hundred preferences.
[307] According to the writer Kazuhisa Fujie and the Italian researcher Guido Tavassi, at first the toys and the various products on Neon Genesis Evangelion made little money, outclassed by the sales of Rei Ayanami's action figures,[30] "and even Bandai was reluctant to market the models of the too unusual and disturbing mecha".
[309] The mecha's image was used for consumer goods such as Adidas shoes,[310] wine bottles and snacks,[311] bags,[312] sportswear and access-dateries,[313] sweatshirts,[314] gloves,[315] underwear,[316][317] children's clothes[318][319] and tamagotchi models.
[325][326] To celebrate the release of the film Evangelion 1.0: You Are (Not) Alone in 2007, Studio Akiyama put a giant figure of Eva-01 about two meters high at the price of one million yen (about ten thousand U.S. dollars) on sale.
[328] At the team's first official competition, the group's Toyota Corolla Axio was repainted with the Evangelion RT-01's color scheme;[329][330] the two racers, Kōki Saga and Kosuke Matsuura, competed wearing two reproductions of the suit used by Shinji.
[346] In 2015, a limited-time event dedicated exclusively to Neon Genesis Evangelion was inaugurated at the Expasa service area in Ashigara, Shizuoka Prefecture, where a six-meter-tall statue of Eva-01, the largest in the world, was displayed.
[351] To coincide with the release of the feature film, a special Evangelion-themed event was held at the Tokyo Sky Tree in 2021, during which the lights of the tower were illuminated in the colors of the Evangelion units from the Rebuild.
[355] The fight sequence between Asuka's Eva-02 and the nine Eva Series present in End was an inspiration for animators such as Yoshimichi Kameda and Yokota Takumi, character designer of Love Live!
Guillermo del Toro and Travis Beacham, director and screenwriter of the feature film, respectively, have stated that they were not directly influenced by Neon Genesis Evangelion, saying that they only saw the series after they had already conceived Pacific Rim.