According to the IMDB, one of the male nurses is played by an uncredited John Merrick (aka John Frederick), who played the lead alien in KILLERS FROM SPACE. I know it's best to be skeptical about unverified info from that site, but after making some direct comparisons, I'd say the odds are pretty good it is the same guy. Based on KILLERS, I always imagined the actor to be sort of a Paul Birch type under the hooded pajamas and protruding eyes, but if that's really him in ALLIGATOR PEOPLE (as the guy who says "Quickest, simplest way, doctor"), my imaginings were way off...turns out he had a whole George Nader-ish thing going on.