Marcus Gillett was born in Amenia, Dutchess County, New York on 28 March 1781. He was the son of Abner Gillett and Hannah Culver. Abner Gillett had served in the Revolutionary War in Regiment 6 of Dutchess County, New York. In Amenia, Marcus married Lucinda Manchester, the daughter of John Manchester and Rachel. His first child Culver M was born in Amenia.

Marcus moved from Amenia in apx 1804 to Middlefield, Otsego, New York with most of his brothers and his father, and Lucinda's brothers Leonard and Joel Manchester, and her father John Manchester. In Middlefield, the rest of his 16 children were born. The children are listed in a family bible kept by his daughter Lucinda who married Selah Pratt. The pages from this bible can be seen on the maney tree at ancestry.com. This bible was copied by Charles Aspinwall, who did family history research in Oswego and Otsego counties. Two of Marcus' children died young in Middlefield. The other 14 lived to adulthood. Eight of his older children married in Middlefield.

While in Middlefield, daughter Sally married Stephen Otis Pratt and moved to Cattaraugus county. His son John B married Rhoda Laura Hubbard and eventually moved to Michigan. His son Culver married Nancy Boyle and moved to Pennsylvania, then back to New York state, and eventually to Oswego City.

In apx 1837 Marcus moved from Middlefield to Mexico, New York along with 6 of his single children, Marcus D, Nathan, German, Hariett R, Daniel A, and George G, and 5 of his married children's families, the family of Polly and Lambert North, Lovina and Sherman Hubbard, Saloma and Rufus Rich, Lucinda Jane and Selah Pratt, Horace Gillett and Henrietta Pratt, and C Marcus' nephew Joel Gillett who is also buried in the Wellwood cemetery.

Marcus stayed in Mexico the rest of his life. He built a fine home in Mexico which still stands along the Gillett Road in Mexico. A picture of this home is shown in the maney tree on ancestry.com, and may also be available from the Town of Mexico Historian.

While in Mexico, 5 of his children married. Marcus D married Lucy (maiden name unknown), and lived in Mexico all of his life. Nathan moved to Eaton Rapids Michigan, with his brother Horace, and later moved to Custer County, Nebraska with his brother George, where both took homesteads. German married Miranda Kenyon, moved to Junius, Seneca, New York, and Wolcott, Wayne, New York. Harriett married Henry Seymour Whitney and lived in Mexico. Daniel A married Lucy Ellsworth and moved to Wisconsin and Kent, Alpine, Michigan. George G married Nancy Springer, and moved to St Lawrence County, New York. Later he moved to Custer, Nebraska where he took a homestead along with his brother Nathan. Later he married Clara Fulford.

Marcus' wife Lucinda died in 1856 and is buried in the Wellwood Cemetery. Marcus died in 1862 and is buried in the Wellwood cemetery. His will and probate papers are on file with the county of Oswego. He left the house and land to his son Marcus D. Marcus D and his ancestors are buried in the Mexico Village Cemetery. His great grandson Carl died in 1944 at which time the property and house were sold out of the family. Some tribute letters to the family are found on the maney tree at ancestry.com.

Of the 11 children that came with him to Oswego County, 3 died in Mexico. One, Harriet Gillett Whitney, is buried in the Wellwood cemetery. One, Marcus D Gillett, is buried in the Mexico Village cemetery. The burial place of daughter Lovina Gillett Hubbard (d 1843) is unknown. Three of the children died within Oswego county, but not in Mexico, Polly Gillett North, Richland, Saloma Gillett Rich, Albion, and Lucinda Gillett Pratt, Oswego. Two of the children stayed in New York, but not in the county, Horace Gillett, Van Buren, and German Gillett, Wolcott. Three of the children moved out of the state (Daniel A, Nathan, and George G Gillett, Michigan then Nebraska). The wife of Marcus' son Horace, Henrietta Pratt Gillett is also buried in the Wellwood Cemetery (died 1860).