- Office of Alumni Engagement records1
- Office of the Bursar Records, 1739/198711
- Office of the President Timothy J. Sullivan records, 1992/2005, bulk 1992/20051
- Office of the President, John Augustine Smith Records, 1814/1944, bulk 1814/18261
- Office of the President. James Blair Records, 1695/17471
- Office of the President. James Madison Records, 1775/1979, bulk 1776/18111
- Ogden Family Papers, 1791/19462
- Ogden family papers, 1801/19793
- Ohio County (W. Va.) Court Records and Miscellaneous Papers, 1772/1954, bulk 1777/193092
- Ohio Historical Papers, 1776/18721
- Oliver Perry Chitwood, Compiler, Research Notes about and Copies of Letters by John Tyler, 1793/18621
- Ollen Lawrence Burnette, Jr. papers, 1815/20141
- Ollinger Crenshaw Papers, 1770/19705
- Opequon Factory Journal, 1813/18291
- Oren F. Morton (1857-1926) Papers, 1799/19263