Carl Josef Bayer, Austrian chemist and academic (d. 1904)
Carl Josef Bayer (also Karl Bayer, March 4, 1847 – October 4, 1904) was an Austrian chemist who invented the Bayer process of extracting alumina from bauxite, essential to this day to the economical production of aluminium.

Bayer had been working in Saint Petersburg to develop a method to provide alumina to the textile industry that used it as a fixing agent in the dyeing of cotton. In 1887, he discovered that aluminium hydroxide precipitated from an alkaline solution which is crystalline and can be filtered and washed more easily than that precipitated from an acid medium by neutralization. In 1888, Bayer developed and patented his four-stage process of extracting alumina from bauxite ore.

In the mid-19th-century, aluminium was so precious that a bar of the metal was exhibited alongside the French Crown Jewels at the Exposition Universelle in Paris 1855. Along with the Hall–Héroult process, Bayer's solution caused the price of aluminium to drop about 80% in 1890 from what it had been in 1854.