James Harris Simons, the award-winning mathematician, renowned investor, and generous philanthropist who co-founded the Simons Foundation, passed away at the age of 86 in New York City. Together with his wife, Marilyn Simons, he established the Simons Foundation in 1994, which has supported scientists worldwide in advancing research in mathematics and basic sciences. Simons’ contributions to the field of mathematics, particularly in string theory, topology, and condensed matter physics, have left an indelible mark on the scientific community. His philanthropic efforts through the Simons Foundation, Simons Foundation International, Math for America, and other initiatives have focused on supporting math and science research, education, and fostering the next generation of mathematicians and scientists.