Collector
- O. Braeske19 objects
- O. C. Stewart49 objects
- O. E. Heeth8 objects
- O. P. Noren6 objects
- Oakland Police Department6 objects
- Oakland Public Museum7 objects
- Ochoa Family1 objects
- Office National Gabonais du Tourisme2 objects
- Office of Alien Property Custodian51 objects
- Office of the Sheriff, Contra Costa County2 objects
- Office of the Sheriff, Santa Cruz County2 objects
- Ohio State Museum1 objects
- Olaf Christian Hansen3 objects
- Olaf P. Jenkins20 objects
- Old Lady Buckskin4 objects
- Old Tom Brown1 objects
- Older University Collections55 objects
- Olive Frank2 objects
- Olive Jennings Youngblood1 objects
- Oliver G. Wolcott2 objects