Albert Abrams, the "King of Quackery," who believed that all that was needed from a patient for diagnosis was a drop of blood, a single hair, or even a handwriting sample as these would give off the unique "vibrations" of that individual. His theories were so popular that none other than Upton Sinclair promoted them in an article for Pearson's magazine.
Wilhelm Reich, the groundbreaking psychiatrist who, in the latter portion of his storied career, discovered "Orgone"--the energy supposedly released during sexual orgasm. According to Reich, absorbing large quantities of Orgone through his Orgone Energy Accumulator would make a person healthier.
Dr. Albert C. Geyser, whose Tricho machine for removing unwanted hair through x-ray depilitation resulted in thousands of women contracting hardened and wrinkled skin, receded gums, never-healing ulcerated sores, tumors, and, of course, cancer.

And if you think quackery is a thing of a past, a sampling of late night television commercials advertising everything from fat burners to magnetic and/or copper pain relievers will cure you of that notion. In fact, in the mid-1990s, a product called "The Stimulator" was advertised on television as a "cure" for pain, menstrual problems, arthritis, and carpal tunnel syndrome. The commercial--featuring Evel Knievel as its spokesperson--was so effective that over 800,000 Stimulators were sold for $88.30 before the FDA shut the company down. Still, the owners made quite a hefty profit on what was simply a one dollar gas grill igniter!