Marion Verhaalen (9 December 1930 – 16 March 2020) was an American composer, music educator, musicologist, and nun who published books about Latin American composers and music. Verhaalen was born in Milwaukee, the fifth child of Carl and Aǵnes Sieberlich Verhaalen. She played accordion and piano by ear as a child, before beginning music lessons at age 12. She started composing organ preludes and interludes in high school. Verhaalen joined the School Sisters of St. Francis in 1949 under the name Sister Mary Vernon, and earned a B.M. in piano at Alverno College; M.M. in piano at Catholic University; and Ed.D. in music education at the Columbia University Teachers College. Her dissertation, which was later published, was entitled The Solo Piano Music of Francisco Mignone and Camargo Guarnieri.