Friedrich Bayer in the context of "Elberfeld"

Bayer AG (English: /ˈbaɪ.ər/, commonly pronounced /ˈbeɪər/; German: [ˈbaɪɐ] ) is a German multinational pharmaceutical and biotechnology company and is one of the largest pharmaceutical companies and biomedical companies in the world. Headquartered in Leverkusen, Bayer's areas of business include pharmaceuticals, consumer healthcare products, agricultural chemicals, seeds and biotechnology products. The company is a component of the EURO STOXX 50 stock market index.

Bayer was founded in 1863 in Barmen as a partnership between dye salesman Friedrich Bayer (1825–1880) and dyer Johann Friedrich Weskott (1821–1876). The company was established as a dyestuffs producer, but the versatility of aniline chemistry led Bayer to expand its business into other areas. In 1899, Bayer launched the compound acetylsalicylic acid under the trademarked name Aspirin. Aspirin is on the World Health Organization's List of Essential Medicines. In 2021, it was the 34th most commonly prescribed medication in the United States, with more than 17 million prescriptions.

Johann Friedrich Weskott (8 October 1821 – 4 October 1876) was a German master dyer and industrialist who co-founded the dyestuffs firm Friedr. Bayer et comp. in 1863 with Friedrich Bayer. The partnership, initially focused on synthetic coal-tar (aniline) dyes such as fuchsine, grew into the company later known as Bayer AG.