Joseph H. Crooker was an ordained Unitarian minister, an active theologian and scholar, a writer, lecturer and author. He was the founder of several Unitarian churches and an activist in many national church-related associations such as the Massachusetts Home Missionary Society, the American Unitarian Association, and the Unitarian Temperance Association. The Unitarians rejected Calvinist doctrines and strived to save souls by what they saw as the simple truth of the Universal Fatherhood of God and the natural brotherhood of man on earth.

Crooker was born in Foxcroft, Maine, on December 8, 1850, a descendant of the Mayflower Pilgrims through John Howland (1592-1673). His contact with Oberlin College is unclear, but the collection reveals an amicable relationship with Ida C. Finney of Oberlin. He was married to Frank E. Burt in 1872, and later remarried to Florence Kollock on June 18, 1896.

Crooker began his career as the minister of the first Unitarian settlement in La Porte, Indiana, serving there for 4 years. He later served as the minister to large and more diverse congregations, composed mainly of students and university professors, in Madison, Wisconsin 1881-1891, and Ann Arbor Michigan, 1898-1905. Between these two positions, Crooker founded a church and several charities in Helena, Montana. His charity work in Montana compelled similar projects in St. Louis, Missouri and Madison, Wisconsin. He spent two years lecturing on the theological topics of his scholarship in the British Isles, 1914-1916.

As an active traveler and public speaker, Crooker gave talks and sermons across the country, from the West Coast to the East Coast, in churches, meeting halls, at university commencements, and to varying types of associations. His work for and participation in several temperance associations ranged from writing anti-alcohol editorials, pamphlets and books, as well as serving as the president of the Unitarian Temperance Association for a decade, to active correspondence with members of the Central China Temperance Association.

A prolific published author, Crooker wrote in the fields of religion, history, and cultural criticism. He wrote: Jesus Brought Back, 1889; Problems in American Society, 1889; A Plea for Sincerity, 1898; Different New Testament Views of Jesus, 1900; The Growth of Christianity; The Supremacy of Kindness, 1900; The Menace to America, 1900; Religious Freedom in American Education, 1903; The New Bible and its New Uses, 1903; The Supremacy of Jesus, 1904; The Church of Today, 1908; The Church of To-morrow, 1911; and Shall I Drink?, 1914. For many years he consistently contributed essays to the national magazine the Christian Register, as well as many other periodicals and newspapers. He died on May 29, 1939 in his home in Kansas City, Missouri.