Marii Hasegawa (September 17, 1918 – July 1, 2012) was a peace activist, known for her fifty years of work with the Women's International League for Peace and Freedom, including serving as its president during the Vietnam War. Hasegawa was born in Hiroshima, Japan. Her family moved to the United States in 1919, after her father, a Buddhist priest, was assigned to serve Buddhists in California. She graduated from the University of California, Berkeley with a BA in home economics in 1938.