Helen Dean King (September 27, 1869 – March 7, 1955) was an American biologist.

Born at Owego, New York, she graduated from Vassar College in 1892, and in 1899 she received her doctorate in philosophy from Bryn Mawr College, with a thesis supervised by embryologist and geneticist Thomas Hunt Morgan.

[1] King 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 an assistant in anatomy in 1908-09.

After 1909, she worked at the Wistar Institute, for more than 40 years, first as an assistant and eventually becoming professor of embryology in 1927 and remaining there until her retirement in 1949.

In later years, she moved her focus to pursue research on gray Norway rats.