Katherine Murray Millett (September 14, 1934 – September 6, 2017) was an American feminist writer, educator, artist, and activist.

She attended Oxford University and was the first American woman to be awarded a postgraduate degree with first-class honors after studying at St Hilda's College, Oxford.

Her writings serve as statements on the feminist, human rights, peace, civil rights, and anti-psychiatry movements.

In 1978, she founded the Women's Art Colony in LaGrange, New York as an institution for women's art and activism. Her books include Sexual Politics (1970), The Prostitution Papers (1973), Flying (1974), Sita (1977), The Basement (1979), Going to Iran (1982), a book about being arrested in Iran; The Loony-Bin Trip (1990), about being involuntarily committed to a psychiatric facility; The Politics of Cruelty (1994); and Mother Millett (2001).