(Farbenfabriken Bayer AG) German chemical and pharmaceutical company, the largest chemical multinational in Europe, founded 1863. In 1990 it manufactured about 10,000 products for industry. Its headquarters are in Leverkusen, Germany.
The company was founded by industrialist Friedrich Bayer (1825–1880), initially to manufacture dyestuffs, but during World War I it was the principal supplier of poison gas and explosives to the German Army. It was reconstituted after World War II. It was a chemist employed by Bayer, C Witthauer, who developed and patented aspirin 1899.