Harry Bailey (1925 - September 8, 1985) was a controversial Australian psychiatrist. He bore the primary responsibility for treatment of mental patients via Deep Sleep Therapy, and other methods, at a Sydney mental hospital.

Whereas most of his compatriots who specialised in psychiatry sought out their training wholly in Britain, Bailey (having, according to his biographers Brian Bromberger and Janet Fife-Yeomans, faked details of his Sydney schooling) worked in Louisiana with Robert Heath of Tulane University. He also studied electroconvulsive therapy under Cedric Howell Swanton back in Australia. During the late 1950s Bailey emerged as one of the most high-profile figures in Australia's mental health professions, being photographed with leading politicians such as New South Wales Premier Joseph Cahill.

Between 1962 and 1979, Bailey was chief psychiatrist at Chelmsford Private Hospital in Sydney's northwest. Under his care, twenty-six Chelmsford patients died , with only perfunctory investigation by authorities. The last of these deaths, that of Miriam Podio, a telecommunications company employee hospitalised for severe depression, occurred in 1977. (Another twenty-four patients, who actually survived Chelmsford, had suicided by 1990.)

As well as deep sleep therapy - which had been pioneered by prominent British psychiatrist William Sargant - patients underwent large amounts of involuntary electroconvulsive therapy, and frequently learned only years afterwards that they had been given it. Female patients also complained of sexual molestation by Bailey . Through this time Bailey and Sargant remained in contact; Bromberger and Fife-Yeomans reported that "Bailey often spoke of the competition between them [him and Sargant] to see who could keep their patients in the deepest coma without killing them."

The resultant scandal broke in the early 1980s, and closed down Chelmsford entirely. A Royal Commission from 1988 to 1990, headed by John Slattery of the New South Wales Supreme Court, produced findings concerning Chelmsford's horrors that ran to twelve volumes. Comprehensively disgraced and finally, if belatedly abandoned by Sargant himself (who wrote to Bailey disassociating himself from the latter's techniques), Bailey swallowed a fatal dose of alcohol and tranquilizers before he could be jailed. He left a note which read: "Let it be known that the Scientologists and the forces of madness have won"; the Citizens Commission on Human Rights, a Scientology-founded organisation, had been active in publicising the Chelmsford patients' sufferings.