Percy Lavon Julian (April 11, 1899 – April 19, 1975) was an American research chemist and a pioneer in the chemical synthesis of medicinal drugs from plants. Julian was the first person to synthesize the natural product physostigmine, and a pioneer in industrial large-scale chemical synthesis of the human hormones progesterone and testosterone from plant sterols such as stigmasterol and sitosterol. His work laid the foundation for the steroid drug industry's production of cortisone, other corticosteroids, and artificial hormones that led to birth control pills.
Julian started his own company to synthesize steroid intermediates from wild Mexican yams. His work helped to greatly reduce the cost of steroid intermediates to large multinational pharmaceutical companies. This significantly expanded the use of several important drugs, including synthetic cortisone. Julian was one of the first African Americans to be allowed to earn a doctorate in chemistry. He was the first African-American chemist inducted into the National Academy of Sciences, and the second African-American scientist, after David Blackwell, inducted into the organization from any field.