The Ultra Series (Japanese: ウルトラシリーズ, Hepburn: Urutora Shirīzu), also known as Ultraman, is a Japanese science fiction media franchise owned and produced by Tsuburaya Productions, which began with the television series Ultra Q in 1966. The franchise has expanded into many television shows, films, comic books, and other media publications, becoming one of the most prominent productions in the Japanese tokusatsu and kaiju genres and pioneering the Kyodai Hero subgenre. The Ultraman series is centered on a fictional alien race of superheroes who often combat kaiju or other aliens.

In Japan, the Ultraman brand generated $7.4 billion US dollars in merchandising revenue from 1966 to 1987. This makes it one of the highest-grossing media franchises of all time. Ultraman was the world's third top-selling licensed character in the 1980s, largely due to his popularity in Asia. References to Ultraman are abundant in Japanese popular culture, much like references to Superman in Western culture.

The franchise is centered on the "Ultras" (Japanese: ウルトラ一族, Hepburn: Urutora Ichizoku), a collective term for the fictional extraterrestrial races spread across its multiverse, with multiple origins given for them. The warriors of these continuities gather at a planet within the M78 nebula (M78星雲, Emu-Nanajūhachi seiun), (not to be confused with the real Messier 78)—also called called the Land of Light (光の国, Hikari no Kuni). Of the 18 billion populating it, 1 million are part of the Inter Galactic Defence Force (宇宙警備隊, Uchū Keibitai) who maintain peace in the universe from alien invaders and monsters. The Ultras that are sent to other worlds are given Color Timers, or "warning lights", which blink with increasing frequency if an Ultra's energy dwindles. They can thus remain active for only a limited span of minutes before its energy is depleted, although it can be replenished afterwards. The main protagonists of each installment end up on Earth and bond with humans or have a human incarnation, their hosts using devices to summon their Ultra’s unique power.

The show Ultraman was followed by many other series. Successors during the Shōwa era are: Ultraseven (1967), Return of Ultraman (1971), Ultraman Ace (1972), Ultraman Taro (1973), Ultraman Leo (1974) and Ultraman 80 (1980). A second generation began during the Heisei era in 1996 with Ultraman Tiga, and the franchise continued, on and off, until its current (third) generation. This began with Ultraman Ginga in 2013.

English-language productions include the 1987 animated movie Ultraman: The Adventure Begins (known as Ultraman USA in Japan) which was produced by Hanna-Barbera; 1990 TV series Ultraman: Towards the Future (Ultraman Great in Japan) which was filmed in Australia; 1993 TV series Ultraman: The Ultimate Hero (Ultraman Powered in Japan) which was filmed in the United States; and 2024 animated film Ultraman: Rising which was produced by Netflix.

In 1993, Tsuburaya Productions and Toei Company co-produced Ultraman vs. Kamen Rider, a crossover with the original Ultraman and Toei's Kamen Rider. This direct-to-video feature is co-copyrighted by both Toei (and its subordinates, Toei Video and Ishinomori Productions) and Tsuburaya Productions.

As of 2025^[update], Tsuburaya Productions accepts 51 Ultras as official. In 2013, the Ultra Series was cited in the Guinness Book of World Records as the record-holder for the most spin-off shows. The Ultraman brand generated $7.4 billion in merchandising revenue from 1966 to 1987, equivalent to more than $20 billion adjusted for inflation. Ultraman was the world's third top-selling licensed character in the 1980s, largely due to his popularity in Asia.

The Ultraman manga, which began in 2011, has sold more than 2.8 million copies as of 2018. At the Tokyo Comic Con on 7 December 2017, Tsuburaya Productions revealed that an anime adaptation of the manga was planned for release in 2019. It was released by Netflix.