Secretin
Secretin was the first hormone to be identified. In 1902, William Bayliss and Ernest Starling were studying how the nervous system controls the process of digestion. It was known that the pancreas secreted digestive juices in response to the passage of food (chyme) through the pyloric sphincter into the duodenum. They discovered (by cutting all the nerves to the pancreas in their experimental animals) that this process was not, in fact, governed by the nervous system. They determined that a substance secreted by the intestinal lining stimulates the pancreas after being transported via the bloodstream. They named this intestinal secretion "secretin". Secretin was the first such "chemical messenger" identified. This type of substance is now called a hormone, a term coined by Bayliss in 1905.
Percy Lavon Julian
Percy Lavon Julian (April 11, 1899 – April 19, 1975) was an African American research chemist and a pioneer in the chemical synthesis of medicinal drugs from plants. He was the first to synthesize the natural product physostigmine, plus a pioneer in the 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 birth control pills.