| Marcellus Boss | |
| Office: | Governor of Guam |
| Term Start: | November 14, 1959 |
| Term End: | August 22, 1960 |
| Predecessor: | Richard Barrett Lowe |
| Successor: | Joseph F. Flores |
| Office2: | Secretary of Guam |
| Term Start2: | November 1, 1957 |
| Term End2: | 1959 |
| Governor2: | Richard Barrett Lowe |
| Predecessor2: | William Corbett |
| Successor2: | A. M. Edwards |
| Office3: | Member of the Kansas State Senate |
| Term Start3: | 1945 |
| Term End3: | 1949 |
| Birth Name: | Marcellus Graeme Boss |
| Birth Date: | 21 January 1901 |
| Birth Place: | United States |
| Death Place: | Kansas, United States |
| Nationality: |  United States |
| Party: | Republican |
| Signature: | Marcellus Boss signature.jpg |
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.[1]
Boss first entered Guamanian administration with a 1957 appointment by President Dwight D. Eisenhower to the post of Secretary of Guam.[2] He also served as a Republican member of the Kansas State Senate[3] prior to becoming involved in the government of Guam.[2] He was city clerk and city attorney of Kiowa, Kansas,[4] and had a thirty-year law career in Columbus, Kansas.[5] He died of a heart attack on March 21, 1967, and was buried at the City Cemetery in Columbus, Kansas.