Considered by Japanese fans to be not only the most popular entry of the Ultra Series, but also one of Japan's greatest sci-fi/superhero TV shows. Due to his huge popularity, the character of Ultra Seven (as well as his alter-ego, Dan Moroboshi, played by Kôji Moritsugu) has appeared in more sequels and spin-offs than any other character in the Ultra Series.
The concept for Dan Moroboshi/Ultra Seven's "Capsule Monsters" (capsules that explode and become giant monsters and change back again upon Dan's command) became the inspiration for Bulma's exploding convenience capsules in Dragon Ball (1986) and for the PokeBalls in the hit video game/TV series Pokémon (1997) (the creators of both series, Akira Toriyama and Satoshi Tajiri, respectively, were big fans of this series).
Creator/producer Eiji Tsuburaya intended Ultraseven (1967) to be the final "Ultra" series. It was indeed the last "Ultra" series to be supervised by Eiji Tsuburaya. But because of the series' success, Tsuburaya Productions started on a story draft in late 1969 titled "Zoku Urutoraman" ("Ultraman Continues"), which was a direct sequel to the original Ultraman: A Special Effects Fantasy Series (1966) (In it, the characters from the original series would return, and Hayata, once again played by Susumu Kurobe, would find a successor to the Beta Capsule). But Eiji had passed away early the following year. The proposed story was ultimately reworked into Return of Ultraman (1971), although Tsuburaya was also going to use it again in 1988 (during the then-popular Ultraman boom).
This was the first English-dubbed Japanese TV series in Hawaii (in 1975). Produced by Tsuburaya's Hawaii branch, it was dubbed by the Commercial Recording Company in Honolulu, and the voice talent consisted of several students from the Speech Department of the University of Hawaii.
The alien robot King Joe (whose body is a combination of four floating alien machine spacecrafts) is named after "Tetsuo Kinjô", who wrote the two-part episode it appeared in.