Carl Heinrich Apstein (19 September 1862, Stettin – 14 November 1950, Berlin) was a German zoologist (over a wide variety of animal life) and botanist (with a focus on phytoplankton and algae).
As a young man he carried out studies of freshwater plankton in Holstein lakes (1890–95).
In May 1898 he obtained his habilitation at Kiel for zoology and comparative anatomy, and a few months later took part as a zoologist in the Deutschen Tiefsee-Expedition (German Deep Sea Expedition) aboard the steamship "Valdivia".
In 1906 he was appointed associate professor in Kiel, and in 1911 became a scientific officer at the Preußischen Akademie der Wissenschaften in Berlin.
In this position he worked as a publisher of scientific journals in the field of zoology, which included editorship of Das Tierreich ("The Animal Kingdom"; from 1927).