Marcellus Graeme Boss (January 21, 1901 – March 21, 1967) was an interim Governor of Guam from November 14, 1959, until his resignation on August 22, 1960. Boss first entered Guamanian administration with a 1957 appointment by President Dwight D. Eisenhower to the post of Secretary of Guam. He also served as a Republican member of the Kansas State Senate prior to becoming involved in the government of Guam. He was city clerk and city attorney of Kiowa, Kansas, and had a thirty-year law career in Columbus, Kansas. He died of a heart attack on March 21, 1967, and was buried at the City Cemetery in Columbus, Kansas.