Bayer (disambiguation)

Bayer is a German multinational pharmaceutical and biotechnology company.

Bayer may refer to:
 * a native or inhabitant of the Free State of Bavaria (Freistaat Bayern)
 * Bayer (crater), a lunar crater
 * Bayer filter, a color filter mosaic also known as a Bayer pattern or Bayer mask, used in digital camera image sensors
 * Bayer designation for star names
 * KFC Uerdingen 05, formerly known as FC Bayer 05 Uerdingen, a German football club
 * Bayer Leverkusen, a German sports and football club
 * Bayer 04 Leverkusen, a German woman's handball club
 * Bayer Esporte Clube, a Brazilian football club
 * Baeyer's reagent, a mild oxidation reagent used in organic chemistry
 * Bayer (surname), list of people with this name