- Ochsner, Amanda (2)
- Odde, David (6)
- Ode, Sigurd Q. (2)
- Odegaard, Robert (1)
- Odiot, Paris, France (Manufacturer) (1)
- Oertwig, All (Guest) (1)
- Ogaard, Louis A (1)
- Ogdahl, Harmon (2)
- Ogden, Laura (2)
- Ogden, Mitchell P. (7)
- Ogden, W. A. (William Augustine), 1841-1897 (4)
- Ogden, W. A.(William Augustine), 1841-1897 (1)
- Ogden, William A. (1)
- Ogilby, John, 1600-1676 (2)
- Ogilvie Flour Mills Co., Ltd (1)
- Ogilvie, Astrid (3)
- Ohio. Division of Lands and Soil (2)
- Ohio. State Geologist (1)
- Ohrt, Del (2)
- Ojea, Hernando, approximately 1560-1615 (descriptor) (1)
