Born in 1892, mentalist Joseph Dunninger was an early example of the magician turned skeptic. He used his skills to debunk mediums and spiritualists who profited from their trickery. He even offered a reward to any medium who could accomplish a feat that he couldn’t duplicate or explain; nobody ever cashed in. He was James Randi before James Randi was James Randi.
In addition to his active and successful efforts taking down phony spiritualists, Dunninger was also a prolific performer on television and radio. You can see him in action above, and check out a recording of his radio program below. Or if you’re a less visual person interested in either mentalism or mediums, Dunninger also authored many books on the subjects, including Popular Magic (1926), Inside the Medium’s Cabinet (1935), and The Art of Thought Reading (1956).