Hans Sommer (born 20 July 1837 in Braunschweig (Brunswick) – 26 April 1922 in Braunschweig) was a German composer and mathematician.

Sommer was born Hans Friedrich August Zincke in Braunschweig in 1837.

Before going into music full-time, Sommer, who had studied mathematics and physics in Braunschweig and Göttingen, was also a noted mathematician. He served as the director of the Braunschweig University of Technology, where he taught mathematics, from 1875 to 1881.

He was most successful as a composer for the theatre. Several of his operas used librettos based on fairy tales and were first produced at Brunswick: Der Nachtwächter (1865), Loreley (1891), Rübezahl und der Sackpfeifer von Neisse (1904), Riquet mit dem Schopf (1907) and Der Waldschratt (1912).Saint Foix, a one-act opera, was given at Munich in 1894 and Der Meermann at Weimar in 1896; Der Vetter aus Bremen (1865), Augustin (1898) and Münchhausen (1896–8) were not performed. His incidental music to Hans von Wolzogen's Das Schloss der Herzen (1891) was first performed in 1897 in Berlin, in concert form. He placed great importance on the literary quality of his librettos, and corresponded with numerous librettists and composers. His many songs, at one time known in England, include the cycles Der Rattenfänger von Hameln, Der wilde Jäger and Sapphos Gesänge; he also wrote orchestral works and male-voice choruses.

Sommer was active in initiating the institution of composer's performance rights and was instrumental in recruiting Richard Strauss to that cause.