Comic Market (コミックマーケット, Komikku Māketto), more commonly known as Comiket (コミケット, Komiketto) or Comike (コミケ, Komike), is a semiannual doujinshi convention in Tokyo, Japan. A grassroots market focused on the sale of doujin (self-published) works, Comiket is a not-for-profit fan convention administered by the volunteer-run Comic Market Preparatory Committee (ComiketPC). Inaugurated on 21 December 1975 with an estimated 700 attendees, Comiket has since grown to become the largest fan convention in the world, with an estimated turnstile attendance of 750,000 in 2019. Comiket is typically held at Tokyo Big Sight in August and December, with the two events distinguished as Summer Comic Market (夏コミ, Natsukomi) and Winter Comic Market (冬コミ, Fuyukomi), respectively.

Comiket is focused primarily on the sale of doujin: non-commercial, self-published works. Approximately 35,000 circles (a term for groups or individuals who create doujin) participate in each edition of Comiket. Different circles exhibit on each day of Comiket; circles producing works on a common subject, such as a particular media franchise or manga genre, are typically grouped on the same day. The most common item sold at Comiket is doujinshi (self-published comics, novels or magazines), while a smaller number of circles sell doujin soft, analog (board/card/etc.) games, music, clothing, and other goods. These are often derivative fan works based on anime, video games, and other media, legal according to Japanese law (shinkokuzai). Since Comiket's inauguration, sample copies of all works sold at Comiket are collected and archived by ComiketPC, with over 2.1 million works having been archived.

Comiket is a major outlet for cosplay enthusiasts. Since Comiket 80 in 2011, restrictions on cosplaying have been gradually relaxed, with a shift from regulating objects (e.g. a ban on items that could be used as weapons) to regulating behavior (e.g. a ban on swinging around long objects). Some general contemporary guidelines include not wearing clothes that are too revealing, not imitating uniformed officers, and being out of cosplay when arriving/departing from Comiket.

Comiket hosts 190 corporate booths each year. This includes both large commercial companies, such as video game studios and manga publishers, as well as celebrity meet and greet sessions.

Comiket is held twice yearly, in August and December. These events are distinguished as "Summer Comic Market" (Natsukomi) and "Winter Comic Market" (Fuyukomi). Since 1995, both events have run for three days each, with Summer Comiket generally occurring Friday to Sunday in mid-August, and Winter Comiket generally occurring the three days prior to New Year's Day. Starting with Comiket 96, the events have been four days long, with the exception of Comiket 103 and 104, which, due to the COVID-19 pandemic, were reduced to two days each. Both events run daily from 10:00 a.m. to 4:00 p.m, with corporate booths open until 5:00 p.m and the entire convention closing an hour early on the final day of the event. Comiket has been held at Tokyo Big Sight in Ariake, Tokyo since 1996. Comiket 98, which was planned for August 2020, was the event's first cancellation in its history as a result of the COVID-19 pandemic; Comiket 99, which would have been held in December 2020 was instead held in December 2021, two years after the last time it was held, and ran for only two days.

Comiket is the largest fan convention in the world, growing from fewer than 10,000 attendees in 1982 to over half a million by 2004. Since 2007, attendee numbers have fluctuated in the region of 500,000 for Winter Comiket and 560,000 for Summer Comiket. Because of the extremely high volume of attendance at Comiket, mobile phone companies set up temporary antennas, while the Tokyo Metro makes special arrangements to accommodate the large crowds. Hour-long queues to enter Comiket during peak hours are common, while some attendees queue up to five hours before the event to ensure early admission. Popular circles are frequently placed near the venue's loading docks so that their queues can extend outside. ComiketPC recommends that first-time attendees arrive in the afternoon to avoid queues.

For every Comiket, a catalog is released that contains information about the event. The catalog includes a list of all participating circles, maps of the convention layout, directions to and from the convention, rules for the convention, results from surveys held among Comiket participants, articles about topics relevant to dōjinshi creators, and one to two pictures ("circle cuts") for every participating circle. It is available in print and DVD-ROM format, and since Comiket 83, is available online behind a partial paywall.

Catalogs are made available for sale at stores two weeks before the event. The print version is roughly the size of an average phone book, while the DVD-ROM version includes features such as advanced search functions and a clickable map. To date, there is no English edition of the catalog available, though the catalog does contain a four-page basic guide for attending Comiket in English, Chinese, and Korean.