Ultraman (ウルトラマン Urutoraman) is a Japanese Tokusatsu Television series that first aired in 1966. Ultraman is a follow-up to the television series Ultra Q, though not technically a sequel or spin-off. The show was produced by Tokyo Broadcasting System and Tsuburaya Productions, and was broadcast on Tokyo Broadcasting System (TBS) from July 17, 1966 to April 9, 1967, with a total of 39 episodes (40, counting the pre-premiere special that aired on July 10, 1966).
Ultraman ultimately became a major pop culture phenomenon in Japan. The shows success spawned dozens of sequels, spin-offs, imitators, parodies, remakes and, of course, video games.
Source: Wikipedia, "Ultraman", available under the CC-BY-SA License.