Starting in 1920, with The Cabinet of Dr. Caligari, a German silent horror movie about a hypnotist who uses his sleepwalking patients to kill by proxy.
So, you know, I have seen some of the great hypnotists and hypnotic professionals work for a long time with someone who is just not hypnotizable, and it doesn't matter.
Because I think a lot of people, if they're not familiar with the psychology of hypnosis, they might think about the stage hypnotists that have people twirling around on stage.