Lilli Hornig (née Lilli Schwenk; born March 22, 1921) is a Czech-American scientist who worked on the Manhattan Project, as well as a feminist activist.
She was born in Ústí nad Labem in 1921. In 1929 her family moved to Berlin, and in 1933 she and her mother came to America, following her father who had moved there to escape the Nazis. She obtained her BA from Bryn Mawr in 1942 and her Ph.D. from Harvard in 1950.
In 1943 she married Donald Hornig, and soon went with him to Los Alamos where he had obtained a job; after being originally asked to take a typing test, her scientific skills were recognized and she was given a job as a staff scientist for the Manhattan Project, in a group working with plutonium chemistry. Later it was decided that plutonium chemistry was too dangerous for women, and so she worked in high-explosive lenses instead. While at Los Alamos she signed a petition urging that the first atom bomb be used on an uninhabited island as a demonstration.
Hornig later became a chemistry professor at Brown University and chairwoman of the chemistry department at Trinity College in Washington, D.C. She also was appointed by President Johnson as a member of a mission to the Republic of Korea that began the founding of the Korea Institute for Science and Technology.
A feminist, she was the founding director of HERS (Higher Education Resource Services) under the auspices of the Committee for the Concerns of Women in New England Colleges and Universities first organized by Sheila Tobias. Hornig also served on equal opportunity committees for the National Science Foundation, the National Cancer Institute, and the American Association for the Advancement of Science. She also was the research chair of the Committee for the Equality of Women at Harvard, and consulted with and participated in many studies of women's science education and careers. She is the author of three books: Climbing the Academic Ladder: Doctoral Women Scientists in Academe, Equal Rites, Unequal Outcomes: Women in American Research Universities, and Women Scientists in Industry and Government: How Much Progress in the 1970's.