John J. "Jack" Dreyfus, Sr. (August 28, 1913 – March 27, 2009) was an American financial expert and the founder of the Dreyfus Funds.
Born in Montgomery, Alabama, Dreyfus was a graduate of Lehigh University in Pennsylvania. He is widely publicized for being the man who "invented" the commonplace mutual fund through direct marketing to the public.
After selling the fund during the early 1970s, Dreyfus became a major proponent of phenytoin as a means to control nervousness and depression when he received a prescription for Dilantin in 1966. Dreyfus' book about his experience with phenytoin, A Remarkable Medicine Has Been Overlooked, sits on the shelves of many physicians courtesy of the work of his foundation. The book Despite well over $100 million in personal financing, his push to see phenytoin evaluated for alternative uses has had little lasting effect on the medical community. This was partially due to Parke-Davis's reluctance to invest in a drug nearing the end of its patent life.
His early television commercials featuring a lion emerging from the Wall Street subway station were successful. According to Barron's Magazine end of Century issue, Jack Dreyfus was considered the 2nd most significant money manager of the last century.
Dreyfus married in 1939 Joan Personette, from whom he was divorced; they had one child, John (Jonny).
His paternal grandfather was a first cousin of Alfred Dreyfus, the protagonist of the French 19th-century anti-Semitic scandal known as the Dreyfus affair.
Jack Dreyfus was also a renowned, championship bridge player.
Jack Dreyfus wrote and published his autobiography titled The Two Lives of Jack Dreyfus--The Lion of Wall Street copyright 1996. Still a proponent of phenytoin, he had his autobiography bound together with his previous work, A Remarkable Medicine Has Been Overlooked. This single volume containing both works, he distributed for free.
John "Jack" Dreyfus died on March 27, 2009.
Dreyfus established the noted Hobeau Farm in Ocala, Florida in the early 1960s where he bred, trained and raced Thoroughbred racehorses. The 2,200-acre (8.9 km2) property was the center of his racing operation. In 1962, Dreyfus hired Hall of Fame thoroughbred trainer Allen Jerkins as head trainer  He sold the property (reduced to 1,830 acres) in February 2005 for $12,750,000
Jack Dreyfus served as Chairman of the New York Racing Association. . He was voted the 1976 Eclipse Award of Merit, Thoroughbred racing's highest honor presented to an individual or entity displaying outstanding lifetime achievement in, and service to, the Thoroughbred industry.
Among his noted horses and victories were Beau Purple, which defeated Kelso in the Man o' War Stakes at Belmont Park in October 1962; Onion which defeated Secretariat in the Whitney Stakes in August 1973; Prove Out which defeated Secretariat in the Woodward Stakes in September 1973; Handsome Boy which defeated Buckpasser in the Brooklyn Handicap in July 1967; Blessing Angelica (mare) which won the Delaware Handicap in 1971 and 1972.