- Christopher Columbus Collection, 1849/18801
- Christopher Wren Singers Records, 1989/2012, bulk 1993/20031
- Civil War Miscellaneous Collection, 1860/2005, bulk 1862/19281
- Clara L. Lawrence Papers, 1763/19391
- Collection of French Language Manuscripts, 1633/1942, bulk 1633/19421
- College of Integrated Science and Technology (CISAT) records, 1987/20041
- Corporal Bruce E. Kline letters, 1918/19191
- Cortland Way Starr letters, 18631
- Craig Family Papers, 1860/1906, bulk 1860/18801
- Craig White Collection, 19681
- Croushorn Family Rockingham Cooperative Farm Bureau Papers, 1932/19581
- Curtis West Harris and Ruth Jones Harris Papers, 1950/20121
- Cushing Family Papers, 1843/18941
- Cyril Buzek, Sr. Papers, 1945/19461
- D. W. Siegfried letters, 1918/19191