- Oragadam
- Orattanādu
- Ottappidāram
- Ottiyanbakkam
- Ovari Paravarnattam
- Odiyam
- Ogalūr
- Olaippādi
- Odayappanvidudi
- Odukapatti
- Odukkūr
- Oduvampatti
- Olaippāraippatti
- Olamampatti
- Olavayal
- Oliyamangalam
- Onāngudi
- Orandaikkudi
- Osuvampatti
- Osuvappatti
- Ovattu Pālampatti
- Ochchanvayal
- Ochchatevankottai
- Odaikkāl
- Odaikulam
- Odakkulam
- Ogamai
- Olaiyūr
- Olugupuli
- Oppilān