- O'Shaughnessy Family Papers, 1857/196527
- O.D. Linder, Compiler, Genealogy Records Regarding the Boyce, Dever, Gibson, and Linder Families, 1860/2000, bulk 1900/20001
- O.J. Morrison Department Stores Company (West Virginia and Ohio) Records, 1910/1985, bulk 1940/19501
- O.W. Riegel Papers, 1900/1992782
- Oak Grove Baptist Church Records, 1853/19591
- Oak Grove Baptist Church collection, 1924/19452
- Obelia "Bee" Graves Papers, 1936/1945, bulk 1937/193917
- Ocean View, Seaside, and Seaview Amusement Parks Collection, 1919/1991, bulk 1940/19794
- Office of Admission records, 1861/20213
- Office of Alumni Engagement records2
- Office of Communications and Marketing subject files, 195045
- Office of Student Aid Records, 1937-2005, 1937/2005, bulk 1940/19701
- Office of University Development Records, 1920/20142
- Office of University Development records2
- Office of the Bursar Records, 1739/19872