John Perdue Gray (August 6, 1825, Halfmoon Township (Pennsylvania) - November 29, 1886, Utica, New York) was an American psychiatrist at the forefront of biological psychiatric theory during the 19th century.

[1] He attended Dickinson College, then the University of Pennsylvania School of Medicine, where he received his medical diploma in 1848.,[2] He spent on year of further studies in Europe, then as a resident at Blockley Asylum in Philadelphia.

[2] In 1850, Gray worked at the Utica Psychiatric Center in New York and was superintendent from 1854 until his death in 1886.

He explained that mental illness can be affected by physical factors relating to an individual.

Utica, NY: Roberts, 1871. https://archive.org/details/insanityitsdepen00gray Gray, John P. Insanity: its Frequency and Some of its Preventable Causes.