Heinrich Otto Wieland (4 June 1877–5 August 1957) was a German chemist. He won the 1927 Nobel Prize in Chemistry for his research into the bile acids.

In 1901 Wieland received his doctorate at the University of Munich while studying under Johannes Thiele.
In 1904 he completed his habilitation, then continued to teach at the university and starting in 1907 was a consultant for Boehringer-Ingelheim.
In 1914 he became associate professor for special topics in organic chemistry, and director of the Organic Division of the State Laboratory in Munich.
From 1917 to 1918 Wieland worked in the service of the (KWI) Kaiser Wilhelm Institute for Physical Chemistry and Elektrochemistry in Dahlem then led by Fritz Haber as an alternative to regular military service.
From 1913 to 1921, he was Professor at the Technical University of Munich. He then moved to the University of Freiburg as successor of Ludwig Gattermann.
In 1925 Wieland succeeded Richard Willstätter as Chemistry Professor at the University of Munich.
In 1941, Wieland isolated the toxin alpha-amanitin, the principal active agent of one of the world's most poisonous mushrooms Amanita phalloides.