Karl Zener was an American psychologist best known for his work in parapsychology. He was born on January 26, 1903, and became famous for developing the Zener cards, a set of 25 cards used to test extrasensory perception (ESP). Each card features one of five symbols: a circle, cross, waves, square, or star. Zener collaborated with the renowned psychologist Joseph B. Rhine at Duke University, where they conducted experiments to explore psychic phenomena. His work contributed to the scientific study of parapsychology, although it remains a controversial field within psychology and science. Zener passed away on March 31, 1997.