There was a 1950's company called Azalea Films or something like that --- they made low budget, B&W, horrible sci-fi movies. Can't remember any of the names. My college room-mate used to collect Azalea's films (in reels). Needed to be drunk to sit through them.

Another one that slipped my mind

Flash Gordon.

On the other side of the scale, what are some of the BEST Sci-Fi movies?
For me -

Alien - The first one