Abstract: Harry Delbert Thiers was an American mycologist know for his taxonomic work on agaricoid and boletoid fungi, with a focus on the mycota of California. He was born on January 22, 1919, in Fort McKavett, Texas, and died August 8, 2000, in southwestern Ohio. In 1959, Thiers accepted a teaching position at San Francisco State University in California. There he mentored numerous students, many who went on to become successful professional mycologist. He retired in 1989, after serving 30 years on the faculty at SFSU and supervising 36 masterâ€™s degree theses, these having made important contributions toward a more complete understanding of the cryptogamic flora of California.