- O'Dwyer, Joseph, 1841-18981
- O'Dwyer, Joseph, 1841-1898, author1
- Ohio. State Board of Health, author.1
- Ohmann-Dumesnil, A. H. (Amant Henry), 1857- author2
- Ohmann-Dumesnil, A. H. (Amant Henry), 1857-1919 author1
- Otis, Fessenden N. (Fessenden Nott), 1825-19002