Now we get to the really fun part of this, er, appreciation of science-fiction films from the 1950s: the
bad ones. Yes, these are the films about which you cannot say that the acting "could have been stronger," or the effects "lacked realism," or the story seemed "weak." These films are so lacking in quality that you can safely say this: These films are sci-fi stinkers.
Or as Frank Zappa put it, these films all exhibit
"Cheepnis," the name of his song saluting sci-fi stinkers that first appeared on the Mothers' 1974 live album
The Roxy and Elsewhere. As Zappa explained in the introduction to "Cheepnis," "the cheaper they are, the better they are," and while he noted that a film's budget, or lack thereof, is not necessarily a factor in its exhibiting "Cheepnis," it does help.
The ten films in this, our final list of 1950s sci-fi films, not only have "Cheepnis" but also some kind of lasting notoriety. Because—let's face it—there are a
lot of bad science-fiction films and not just from the 1950s, and I'll leave it to
Elvira, Mistress of the Dark, to memorialize those. For example,
The Giant Gila Monster (1959) is certainly bad—the special effects include an obvious model train and an ordinary lizard in a diorama to make it seem "giant"—but no one in the cast had any fame nor went on to any fame, the narrative and dialogue are not memorably atrocious, so it is merely bad but not notably so.