Susan O'Neal Stryker (born 1961) is an American professor, author, filmmaker, and theorist whose work focuses on gender and human sexuality. She is Professor of Gender and Women's Studies, former director of the Institute for LGBT Studies, and founder of the Transgender Studies Initiative at the University of Arizona, and is currently on leave while holding an appointment as Barbara Lee Distinguished Chair in Women's Leadership at Mills College. Stryker also serves on the Advisory Council of METI (Messaging Extraterrestrial Intelligence). A transgender woman, she is the author of several books about LGBT history and culture.