Hans Ris (June 15, 1914 – November 19, 2004) was an American cytologist and pioneer electron microscopist. His studies of chromosome structure revealed the importance of non-histone proteins, and along with evolutionary biologist Lynn Margulis, he was one of the first to recognize that blue-green algae were a special type of bacteria. He coined the term genophore for prokaryote DNA to highlight its differences from the eukaryal chromosome. Ris was a founding member of the American Society for Cell Biology and received the Distinguished Scientist Award by the Microscopy Society of America in 1983.