The first x-ray was invented by Wilhelm Rontgen in 1895.
Rontgen had been expelled in high school for drawing a cartoon of one of his teachers.
He couldn’t attend University without a diploma, but finally got into a Polytechnic Institute, and became a mechanical engineer.
Rontgen was experimenting with a vacuum tube that was lined with aluminum and had a cathode ray inside. He had put a cardboard covering over the tube to protect it. But he saw that a chemical reaction had been left on the cardboard around the tube, and eventually learned that it was from a new type of ray, which he called the “x-ray”.
The first x-ray he took was of his wife’s hand!
Despite this discovery which changed the world, and also in spite of inheriting a great deal of money from his father, Roentgen died in bankruptcy, and had ordered that all of his scientific writings be destroyed upon his death. But fortunately, his greatest contribution had already been made available for the world.