Here are some great names for cats which all start with the letter O.
| Oatcake | Olivia | Oscar |
| Obelix | Olivier | Osiris |
| Obi | Ollie | Oswald |
| Octavia | Oops | Othello |
| Octopussy | Ophelia | Otis |
| Odin | Oreo | Ozzie |
| Olaf | Orpheus | Ozzy |
| Olive | Orville |
Here are some great names for cats which all start with the letter O.
| Oatcake | Olivia | Oscar |
| Obelix | Olivier | Osiris |
| Obi | Ollie | Oswald |
| Octavia | Oops | Othello |
| Octopussy | Ophelia | Otis |
| Odin | Oreo | Ozzie |
| Olaf | Orpheus | Ozzy |
| Olive | Orville |