Robert Hanham Collyer (1814 – c. 1891) was a British physician, phrenologist, mesmerist, lecturer, author, and inventor mostly active on the east coast of America and Canada during the 19th-century.

He was also involved in a number of scandals and rivalries, including a claim that he originated inhalation anesthesia for surgery before William T. G. Morton, who is generally credited with the discovery.

[2][3][4] He studied phrenology under Johann Gaspar Spurzheim in Paris;[5] and, then, attended classes at London University, where he studied medicine with John Elliotson — the founder and first President of the London Phrenological Society, and an early advocate of mesmerism in England (and, later, joint editor of The Zoist: A Journal of Cerebral Physiology & Mesmerism, and Their Applications to Human Welfare) — for at least two years, but did not go on to graduate.

[1][2][6] In March 1836, aged 22, he and his parents and siblings migrated to America, where he traveled along the east coast of the United States and Canada giving lectures on phrenology.

[45][46][47][48] He was also known for a very public scandal in which his wife was found in bed with another man, in Louisville, Kentucky, on September 25, 1838: the eminent English novelist Captain Marryat, author of The Children of the New Forest, and Mr Midshipman Easy.

[54][55] Collyer was also a prolific inventor, with a list of patents which ranged from a method for crushing quartz, ways to manufacture paper products, and a new covering for electric telegraph cables.

[56] He practiced medicine for some time in Jersey, joined the California Gold Rush, and was in charge of a cholera hospital in Mexico before returning to England to focus on his more profitable inventions.