Ernst Anton Nicolai (7 September 1722 – 28 August 1802) was a German physician and chemist.

In 1745, Nicolai earned his medical doctorate from the University of Halle, where he was a disciple of Johann Heinrich Schulze and Friedrich Hoffmann.

At Halle, he gave lectures on theoretical subjects in the fields of pathology, physiology and pharmacology, later giving clinical lectures on diseases of the eye and childhood maladies.

[1][2] In 1758, Nicolai was appointed professor of theoretical medicine at the University of Jena.

During the following year, he became a professor of chemistry and clinical medicine at Jena, a position he held until his death in 1802.