Ultra Seven (partially lost English dubs of TV series; 1975/1985)
Ultraseven (ウルトラセブン Urutora Sebun) is the third entry in Japan's long-running Ultra Series and is the sequel to Ultraman. The show is immensely popular, both in Japan and otherwise, and the show received two English dubs, as well as a subtitled DVD release by Shout Factory. However, both English dubs have missing episodes, and a few episodes that have been banned from airing.
First English Dub
The first English dub aired back in 1975, on Hawaii's KHON-TV channel. According to the existing information, all episodes were dubbed and broadcast. However, due to the age of the dub, and the fact that recording TV wasn't very easy at that time, only three episodes have survived of this dub: Episodes 21, 22, 35, and 49. It's possible that recording of other episodes exists.
Turner Program Services & CINAR Dub
The second English dub of Ultraseven, this dub is far more well-known. Turner and CINAR produce this dub in 1985 for a run-in syndication. This version of the dub features new opening and closing credits and new eyecatchs. However, the dub wasn't picked up and it was shelved until 1994 when Ultraseven was broadcast on Toons 'Till Noon and MonsterVision blocks on TNT. However, between 1985 and 1994, Turner lost the masters of episodes 5, 6 and 7, and because of this, they were skipped by the dub. When the Turner licensed expired, all the masters were reverted and collected by Tsuburaya Productions. While this dub can be found online, it has received no official release.
There are two episodes that have been banned from airing on Japanese TV or from getting a release on home media. The first is Episode 12, From a Planet with Love, an episode about space vampires stealing blood from young women utilizing a powerful monster. The episode was banned after receiving complaints that the monster of the day's design resembled hibakusha, survivors of the atomic bombings who are subjected to terrible discrimination and was considered to be in poor taste. While this episode was aired as a part of the Turner English dub (where it is called Crystallized Corpusels) the episode was skipped by the Shout Factory release, as well as all other Japanese DVD releases.
The second banned episode is Episode 26, Super Weapon R-1, which was banned from airing in 2011 after the Fukushima Daiichi nuclear disaster. This episode is still a part of the Shout Factory release, however.