Johann Friedrich Wilhelm Adolf von Baeyer (October 31, 1835 - August 20, 1917) was a German chemist who synthesized indigo, and was the 1905 recipient of the Nobel Prize in Chemistry. Born in Berlin, he initially studied mathematics and physics at Berlin University before moving to Heidelberg to study chemistry with Robert Bunsen. There he worked primarily in August Kekulé's laboratory, earning his doctorate (from Berlin) in 1858. He became a lecturer at the Berlin Trade Academy in 1860, and a Professor at Strasbourg in 1871. In 1875 he succeeded Justus von Liebig as Chemistry Professor at the University of Munich.

Baeyer's chief achievements include the synthesis and description of the plant dye indigo, the discovery of the phthalein dyes, and the investigation of polyacetylenes, oxonium salts, and uric acid derivatives (including the discovery of barbituric acid, the parent compound of the barbiturates). His contributions to theoretical chemistry include the 'strain' (Spannung) theory of triple bonds and small carbon rings. In 1872 he experimented with phenol and formaldehyde, almost preempting Leo Baekeland's later discovery of Bakelite.

In 1881 the Royal Society of London awarded Baeyer the Davy Medal for his work with indigo. In 1905 he was awarded the Nobel Prize in Chemistry "for his work on organic dyes and hydroaromatic compounds".