Thomas Percival FRS FRSE FSA (29 September 1740 – 30 August 1804) was an English physician, health reformer, ethicist and author who wrote an early code of medical ethics.

The latter was initially circulated privately as a book on jurisprudence in 1794 and as a result of solicited comments from colleagues then published in an expanded form with a change in title to Medical ethics in 1803.

Percival had been asked by the Manchester Royal Infirmary to help with an internal dispute and became particularly concerned with the divisions that had arisen among the different branches of the profession – the physicians, surgeons, and apothecaries with their different backgrounds of training (university, hospital, and apprenticeship respectively).

He led a group of doctors to supervise textile mills, their report influenced Robert Peel's to introduce the Health and Morals of Apprentices Act 1802.

His personality, his interest in sociological matters, and his close association with the Manchester Infirmary led to the preparation of a scheme of professional conduct relative to hospitals and other charities from which he drafted the code that bears his name.

[9] As one expert writes, "The Percivalian code asserted the moral authority and independence of physicians in service to others, affirmed the profession's responsibility to care for the sick, and emphasized individual honor.