Donor
- O. E. Heeth8 objects
- O. E. Hovgaard2 objects
- O. P. Noren6 objects
- Oakland Public Museum13 objects
- Oakland Symphony Youth Orchestra1 objects
- Octavia Page Carleton1 objects
- Odd S. Halseth1 objects
- Office National Gabonais du Tourisme31 objects
- Office of Alien Property Custodian53 objects
- Office of the Sheriff, Contra Costa County2 objects
- Olaf P. Jenkins23 objects
- Older University Collections4,530 objects
- Olga M. Leino1 objects
- Olive Frank2 objects
- Olive Gillian1 objects
- Oliver P. Webb4 objects
- Olline Riddell12,815 objects
- Omer C. Stewart103 objects
- Ondina F. Leal11 objects
- Oregon Historical Society60 objects