Women, Race & Class, and a lifetime of showing that prisons, race and gender are one question rather than three.
Angela Davis (born 1944) studied philosophy under Herbert Marcuse and has spent the decades since making an argument that the discipline is slow to call philosophy: that the prison is not a response to a social problem but a way of not addressing one, and that race, class and gender are not separate axes you can hold steady while you examine the others.
Women, Race & Class came out in 1981 and is still the book to hand someone who thinks the history of feminism is a single story. She is a working philosopher whose work happens to have consequences outside the seminar room, which is supposed to be the point.