Works O
| OFFCORE | Work | |
| Odysseus | Work | |
| Oedipus Rex | Work | |
| Okon Fuoko | Work | |
| Olen parhaimmillani | Work | |
| Ondine | Work | |
| Onegin | Work | |
| Onnen linna | Work | |
| Opri ja Oleksi | Work | |
| Oracle | Work | |
| Orion | Work | |
| Orlando | Work | |
| Orlando Paladino | Work | |
| Orpheus and Eurydice | Work | |
| Orpheus in the Underworld | Work | |
| Osiris | Work | |
| Otello | Work | |
| Otello (Matšavariani) | Work |