The scariest
movie ever was
Target Earth (1954). At least, that's what I thought when my friend and I saw it on TV when our ages were still in single digits. It scared the daylights out of us. Although I didn't realize it at the time, the "robot army" was one robot. That's all the film's low budget allowed.
YouTube uploader
1954clips calls it "
The world's silliest robot attacks."