Isaac Thomas Littleton (1921- ) received an A.B. from the University of North Carolina in 1943, an M.A. from the University of Tennessee in 1950, and M.S. and Ph.D. in library science from the University of Illinois at Urbana-Champaign in 1951 and 1968. He came to the D. H. Hill Library at the North Carolina State College of Agriculture and Engineering (later North Carolina State University) in 1959, as head of technical services and assistant director of libraries. Appointed acting director in 1964, Littleton succeeded Harlan Craig Brown as director of libraries in 1967, and retired in 1987.

Under Littleton's leadership, the D. H. Hill Library's collections increased dramatically, along with its physical space. During his tenure, the library became part of the Online Computer Library Center, the Southeastern Library Network, the Triangle Research Libraries Network, and the Association of Research Libraries. A member of several professional and honorary societies, Littleton was chairman of the University of North Carolina system's University Library Advisory Council, the Association of Southeastern Research Libraries, and the Southeastern Library Network.