Charles Ripley Gillett was born on November 29, 1855, in New York, New York.

He was a clergyman, librarian, and author. He was educated at the University of New York (B.A., 1874, B.Sc., 1876, M.A., 1877, D.D., 1898) and at the University of Berlin (1881-1883). In 1883, he began his post of Librarian at the Union Theological Seminary, New York that lasted until 1908, becoming Librarian Emeritus from 1929 to 1948. As a librarian, Gillett was involved with the acquisition of funds for the McAlpin Collection, the Gillett Collection of British history and theology, he oversaw the transfer of the library’s 60,000 volumes to Union’s newly-expanded campus on Park Avenue and guided the development of the library’s collection of books and pamphlets as Union transitioned to an interdenominational seminary at the turn of the 20th century. He also served as Secretary of the Faculty (1898-1929), Registrar (1898-1900, 1908-1924), Dean of Students (1913-1929), and Alumni Secretary (1913-1948). Gillett was ordained with the New York Presbytery in 1886. From 1891 to 1897 he worked as an editor at the Magazine of Christian Literature. In 1899, he received an honorary degree of Doctor of Humane Letters (L.H.D.) from Beloit College, Wisconsin. From 1900 to 1910 he was an Assistant Curator at the Department of Antiquities at the Metropolitan Museum of Art. He wrote the book "Burned Books: Neglected Chapters in British History and Literature" (2 vols, 1932).

In 1881, he married Kate VanKirk (1857–1940). He died on September 3, 1948, in Norfolk, Connecticut.