Total Recall (1990)
As Arnold Schwarzenegger's Quaid makes his way through airport security in the 1990 action/sci-fi film Total Recall, his violent intentions are quickly discovered. An X-ray scanner records an image of his gun-toting skeleton in the boarding area of an interplanetary shuttle.
Throughout the scene, we also see a whole family of boarding "skeletons" -- husband, wide, kids and a dog -- parading though the security checkpoint.
We can only speculate that some future TSA official clung to the image, leading to the security theater that herds airline passengers through full body scans.