Otto Bayer (November 4, 1902 in Frankfurt– August 1, 1982 in Burscheid) was a German industrial chemist at IG Farben who was head of the research group that discovered the polyaddition for the synthesis of polyurethanes out of polyisocyanate and polyol. Dr. Bayer was not related to the founding family of Bayer Corp. Today polyurethanes are ubiquitous throughout modern life. He was a member of the board of directors and of the supervisory board of Bayer, and was also vice chairman of the supervisory board of Cassella in the 1950s.