Hans Spemann (27 June 1869 – 9 September 1941) was a German embryologist who was awarded a Nobel Prize in Physiology or Medicine in 1935 for his discovery of the effect now known as embryonic induction, an influence, exercised by various parts of the embryo, that directs the development of groups of cells into particular tissues and organs.

Hans Spemann was born in Stuttgart, the eldest son of publisher Wilhelm Spemann and his wife Lisinka, née Hoffman. After he left school in 1888 he spent a year in his father's business, then, in 1889–1890, he did military service in the Kassel Hussars followed by a short time as a bookseller in Hamburg. In 1891 he entered the University of Heidelberg where he studied medicine, taking his preliminary examination in 1893. There he met the biologist and psychologist Gustav Wolff who had begun experiments on the embryological developments of newts and shown that, if the lens of a developing newt's eye is removed, it regenerates.

In 1892 Spemann married Klara Binder: the couple were to have two sons. In 1893–1894 he moved to the University of Munich for clinical training but decided, rather than becoming a clinician, to move to the Zoological Institute at the University of Würzburg, where he remained as a lecturer until 1908. His degree in zoology, botany, and physics, awarded in 1895, followed study under Theodor Boveri, Julius Sachs and Wilhelm Röntgen.