Hermann Vallentin (24 May 1872 – 18 September 1945) was a German actor born in Berlin. He was the son of a Jewish timber merchant and factory owner, Felix Vallentin. He was the older brother of actress Rosa Valetti. After training as an actor at the Royal Theatre in Berlin with Max Grube and Hans Oberländer, he received his first engagement at the Central-Theatre in Berlin in the 1895/96 season. In the next few years, appearances on various Berlin stages followed.

From 1914, Vallentin was also a film actor. He mostly embodied fatherly figures, patriarchs and directors, but also small-minded philistines. In the 1931 film version of Der Hauptmann von Köpenick, he played the uniform tailor Adolph Wormser.