Phyllis Jacobson (1922 – March 2, 2010) was an American socialist. Together with her lifetime political and personal partner Julius Jacobson, she co-edited the independent left journal New Politics from the 1960s until the end of the 20th century.
Born into a New York City Jewish working-class family, she joined the Young People's Socialist League (YPSL) affiliated with the Socialist Party as a teenager in the 1930s, where she met Julius Jacobson. Together they were persuaded of revolutionary socialism in its Trotskyist expression and they played a role in successor youth organizations to the YPSL associated with the Socialist Workers Party and the Workers Party. Between the 1930s and 1950s, at a time when the Communist Party had sway over much of the left in the United States, the Jacobsons were associated with a radically democratic current of the socialist movement which rejected Stalinist bureaucratic collectivism and understood the Soviet Union to be a perversion of socialism because of its lack of workers' control over industry and society. They were founding members of the Independent Socialist League, for which she was briefly the Manhattan organizer and which espoused Third Camp socialism.