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. There he was involved in weapons research for instance finding new synthetic routes for mustard gas. He is also credited with the first synthesis of Adamsite.

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 (he also assumed responsibility for Gattermanns infamous cookbook). In Freiburg he started working on toad poisons and bile acids. In association with Boehringer Ingelheim he worked on synthetic alkaloids such as morphine and strychnine

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.

Wieland tried successfully to protect people, especially Jewish students, who were "racially burdened" after the Nuremberg Laws. Students who were expelled because they were "racially burdened" could stay in Heinrich Wieland's group as chemists or as "Gäste des Geheimrats" (guests of the privy councillor). After collecting money for Kurt Huber's widow Clara Huber, Hans Conrad Leipelt, a student of Wieland, was sentenced to death.

Heinrichs father, Theodor Wieland (1846 – 1928) was a pharmacist with a doctorate in chemistry. He owned a gold and silver refinery in Pforzheim. Heinrich Wieland was a cousin of Helene Boehringer, the wife of Albert Boehringer, who was the founder of Boehringer Ingelheim. From 1915 to the end of 1920, he was advisor at Boehringer-Ingelheim and during this time he established the first scientific department of the company.

Eva Wieland, Heinrich Wieland's daughter, was married to Feodor Lynen on 14 May 1937.

Since 1964, the Heinrich Wieland Prize has been awarded annually to promote research on chemistry, biochemistry, physiology and clinical medicine of lipids and related substances. The prize is among the most treasured international science awards and has a successful history of over 40 years. To date it has been presented to 58 scientists. The Heinrich Wieland Prize is sponsored by Boehringer Ingelheim and awarded by an independent Board of Trustees.