1. Melvil Dewey (December 10, 1851–December 26, 1931)

Melville Louis Kossuth Dewey grew up in New York state. In 1870, he enrolled in Amherst College, in Massachusetts; he graduated four years later with a degree in mathematics. While a student there, he became assistant librarian to help pay for his college expenses and became interested in topics such as shorthand and spelling reform. His ideas for better organizing the college library laid the foundation for what became the DDC.

He first published A Classification and Subject Index for Cataloguing and Arranging the Books and Pamphlets of a Library anonymously in 1876. It received wide publicity in the same year when specimen classes and an even longer introduction were published in a report, Public Libraries in the United States, by the US Bureau of Education as a volume on the state of the art of librarianship. Dewey would go on to co-found the American Library Association (ALA) and simplify the spelling of his own first name to Melvil.

By 1883, Dewey had moved to Columbia College (now Columbia University), where he helped reorganize the library and create a coeducational library school. He left in 1888 to become Secretary of the Board of Regents of the University of the State of New York (SUNY) and Director of the New York State Library. On January 1, 1906, he resigned from the State Library, due primarily to charges leveled against him regarding the anti- Semitism of the Lake Placid Club, of which he was the primary founder. At this point, he formally retired, but continued to be involved in development of the classification.

His legacy is mixed. The DDC, of course, lives on, albeit very different in many respects than during his lifetime. While he helped bring women into professional librarianship, he was also censured and driven out of the ALA after harassing multiple women. Not until 2019 did the ALA agree to rename its highest honorary medal, theretofore known as the Melvil Dewey Medal.

2. Walter S. Biscoe (February 14, 1853–September 22, 1933)

Walter Stanley Biscoe was a close associate of Melvil Dewey and a major figure in the development of the DDC while working with Dewey at Columbia College in New York City. Biscoe was a classmate of Dewey's at Amherst and was associated with the editing of the DDC from the First to the 13th Editions, 1874–1927.