Helen Dean King (1869-1955) was an American biologist. Born at Owego, N. Y., she graduated from Vassar College in 1892 and in 1899 received her doctorate in philosophy from Bryn Mawr College, where she was fellow and student assistant in biology from 1897 to 1904. She taught physiology at Miss Baldwin's School, Bryn Mawr, from 1899 to 1907, was research fellow at the University of Pennsylvania in 1906-08, and served as assistant in anatomy in 1908-09 and as an associate after 1909 at the Wistar Institute. She was also an assistant at Woods Hole, Mass. Her investigations dealt largely with problems of sex determination.
At Wistar, she worked to help breed the Wistar rat, a strain of genetically homogeneous white rats that became widely used in biological research.