William Gregory (25 December 1803 - 24 April 1858) was a Scottish physician who is best known for his work in chemistry. He studied under and translated some of the works of Liebig, the noted German chemist. Gregory also had interests in mesmerism and phrenology. His greatest contribution came in 1831 when he published a process for isolating morphine hydrochloride in a high state of purity and at a cost no greater than that of an equivalent dose of laudanum.