Otaku (Japanese: おたく, オタク, or ヲタク) is a Japanese word that describes people with consuming interests, particularly in anime, manga, video games, or computers. Its contemporary use originated with a 1983 essay by Akio Nakamori in Manga Burikko. Otaku may be used as a pejorative with its negativity stemming from a stereotypical view of otaku as social outcasts and the media's reporting on Tsutomu Miyazaki, "The Otaku Murderer", in 1989. According to studies published in 2013, the term has become less negative, and an increasing number of people now identify themselves as otaku, both in Japan and elsewhere. Out of 137,734 teens surveyed in Japan in 2013, 42.2% self-identified as a type of otaku.

Otaku subculture is a central theme of various anime and manga works, documentaries and academic research. The subculture began in the 1980s as changing social mentalities and the nurturing of otaku traits by Japanese schools combined with the resignation of such individuals to what was then seen as inevitably becoming social outcasts. The subculture's birth coincided with the anime boom, after the release of works such as Mobile Suit Gundam before it branched into Comic Market. The otaku subculture continued to grow with the expansion of the internet and media, as more anime, video games, shows, and comics were created. The definition of otaku subsequently became more complex, and numerous classifications of otaku emerged. In 2005, the Nomura Research Institute divided otaku into twelve groups and estimated the size and market impact of each of these groups. Other institutions have split it further or focus on a single otaku interest. These publications classify distinct groups including anime, manga, camera, automobile, idol and electronics otaku. In 2005, the economic impact of otaku was estimated to be as high as ¥2 trillion (US$18 billion).