Edgar Cayce (Hopkinsville, 18 maart 1877 - Virginia Beach, 3 januari 1945) was een paranormaal medium en helderziende die zich presenteerde als een 'helderziend diagnosticus' (oorspronkelijk in het Engels: 'psychic diagnostician').
Tijdens sessies viel Cayce graag in trance, waarna het hem mogelijk was om vragen van derden te beantwoorden over hun gezondheid, dromen, vroegere levens en zakelijk advies. In zekere zin liep hij vooruit op veel thema's, die later door de New Age zouden worden opgepakt. Vanwege de trance, waarin Cayce tijdens zijn sessies viel, werd hij door Jess Stearn de slapende profeet genoemd. Diens boek over Cayce droeg de gelijknamige titel "The sleeping prophet"
Edgar Cayce (pronounced Casey) is known as one of America's greatest psychics. His followers maintain that Cayce was able to tap into some sort of higher consciousness, such as a god or the akashic record, to get his "psychic knowledge." He used this "knowledge" to predict that California will slide into the ocean and that New York City will be destroyed in some sort of cataclysm. He predicted that in 1958 the U.S. would discover some sort of death ray used on Atlantis. Cayce is one of the main people responsible for some of the sillier notions about Atlantis, including the idea that the Atlanteans had some sort of Great Crystal. Cayce called the Great Crystal the Tuaoi Stone and said it was a huge cylindrical prism that was used to gather and focus "energy," allowing the Atlanteans to do all kinds of fantastic things. But they got greedy and stupid, tuned up their Crystal to too high a frequency and set off volcanic disturbances that led to the destruction of that ancient world. He made other predictions concerning such things as the Great Depression (that 1933 would be a good year) and the Lindbergh kidnapping (most of it wrong, all of it useless), and that China would be converted to Christianity by 1968. He also claimed to be able see and read auras, but this power was never tested under controlled conditions. However, Edgar Cayce is best known for being a psychic medical diagnostician and psychic reader of past lives.