Shipmates
- O -
| Name | Rank(s) | Ship(s) |
| Oddy, G. | AB | Germanic |
| Ogilvie, H. | AB | Runic |
| Oland, A. | AB | Charles Cotesworth |
| Olden, J. | AB | Oceanic |
| Ollison, W. | AB | Runic |
| Olliver, A. | AB, QM | Adriatic, Olympic, Titanic |
| Olltroff, R. | AB | Iquique |
| Olsen, A. | AB | Celtic |
| Olsen, M. | AB | Iquique |
| Olsen, N. | AB | St. Cuthbert |
| Omohundre, A. C. | OS | Lydgate |
| Orr, J. S. | AB | Arabic, Olympic |
| Osman, F. | AB | Adriatic, Titanic |
| Osman, P. | AB, LO | Adriatic, Olympic |
| Otter, J. W. | AB | Olympic |
| Ottey, A. | AB | Olympic |
| Ovens, R. D. | AB | Celtic |
| Owen, A. | AB | Oceanic |
| Owen, D. | Chief Mate | Adriatic |
| Owen, F. | AB | Runic |
| Owens, E. | AB | Oceanic, Cedric |
| Owens, J. | AB | Arabic |
| Owens, R. | AB | Oceanic |
| Owens, T. | AB | Adriatic |
| Owens, W. | AB | Celtic |
| O'Brien, S. | AB | Oceanic |
| O'Clay, D. | ? | Medic |
| O'Connor, P. | AB | Oceanic |
| O'Hure, L. | AB | Adriatic |
| O'Loughlin, W. F. N. | Surgeon | Oceanic, Adriatic, Olympic,Titanic |
| O'Neill, F. | AB | Oceanic |
| O'Rourke, H. | AB | Arabic |
| O'Shea, Barth | AB | Cedric, Oceanic |