When Cleveland Gillett was born on 16 June 1839, in South Byron, Byron, Genesee, New York, United States, his father, Moses Gillett, was 40 and his mother, Polly Gillett, was 35. He had at least 1 son and 2 daughters with Lucella Ames. He lived in Niles Township, Berrien, Michigan, United States in 1870 and Batavia, Genesee, New York, United States in 1875. He died on 25 July 1937, in Byron, Genesee, New York, United States, at the age of 98.