Karl Hermann Struve (October 3 1854 – August 12 1920) was a German astronomer born in Russia, part of the famous Struve family of astronomers. In Russian, his name is sometimes given as German Ottovich Struve (Герман Оттович Струве) or German Ottonovich Struve (Герман Оттонович Струве); however, he spent much of the latter part of his career in Germany.

He was less well-known than his famous grandfather Friedrich Georg Wilhelm von Struve or his father Otto Wilhelm von Struve or his nephew Otto Struve. His brother was Ludwig Struve. Unlike other members of his family, he moved back to Germany from Russia and spent most of his career there.

He obtained his Ph.D. at the University of Tartu in 1882 and joined the staff of Pulkovo Observatory, studying the satellites of Saturn among other things. He succeeded his father Otto Wilhelm von Struve as the senior astronomer in 1890. However in 1895 he retired and returned to Germany, becoming director of Königsberg Observatory . From 1904 until his death he was director of the Berlin-Babelsberg Observatory .

He won the Gold Medal of the Royal Astronomical Society in 1903.

The asteroid 768 Struveana was named jointly in his honour and that of Otto Wilhelm von Struve and Friedrich Georg Wilhelm Struve.