Georg Ernst Stahl (22 October 1659 – 24 May 1734) was a German chemist and physician.

He was born at Ansbach. Having graduated in medicine at the University of Jena in 1683, he became court physician to Duke Johann Ernst of Sachsen Weimar in 1687. From 1694 to 1716 he held the chair of medicine at Halle, and was then appointed physician to King Friedrich Wilhelm I of Prussia in Berlin. He died in Berlin.

In chemistry he is chiefly remembered in part with the obsolete phlogiston theory, the essentials of which, however, he owed to J.J. Becher. He also propounded a view of fermentation which in some respects resembles that supported by Justus von Liebig a century and half later. In medicine he professed an animistic system, in opposition to the materialism of Hermann Boerhaave and Friedrich Hoffmann.

He hypothesized that all matter had a vital force, or a soul of sorts. He burned wood, and crediting the lower mass of the ashes compared to the original wood to the leaving of the vital force, because the wood had been killed in the process of burning. This theory was replaced by that of Antoine Lavoisier.

His views had been criticized by Gottfried Leibniz with whom he exchanged letters, later published in a book as Negotium otiosum seu σκιαμαχία (1720).

The most important of his numerous writings are Zymotechnia fundamentalis sive fermentalionis theoria generalis (1697), which contains the phlogistic hypothesis; Specimen Becherianum (1702); Experimenta, observationes, aniniadversiones ... chymicae et physicae (1731); Theoria medica vera (1707); Ars sanandi cum expectalione (1730).