| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
|---|
| Oak Forest | city | Indiana | United States | 39.38472 | -85.08528 | 961 | 1857 |
| Oak Grove | city | Indiana | United States | 37.83611 | -88.02167 | 347 | 1046 |
| Oak Grove | city | Indiana | United States | 41.28778 | -86.48611 | 718 | 2665 |
| Oak Hill | city | Indiana | United States | 38.30444 | -87.37444 | 495 | 3085 |
| Oak Lodge | city | Indiana | United States | 41.59472 | -85.2025 | 948 | 3194 |
| Oak Park | city | Indiana | United States | 38.30556 | -85.69639 | 416 | 62237 |
| Oak Tree Crossroads | city | Indiana | United States | 39.37222 | -85.00306 | 902 | 2751 |
| Oakdale | city | Indiana | United States | 40.76833 | -86.05361 | 669 | 13154 |
| Oakdale | city | Indiana | United States | 39.01972 | -85.56194 | 698 | 4402 |
| Oakford | city | Indiana | United States | 40.41917 | -86.10417 | 859 | 37690 |
| Oakland City | city | Indiana | United States | 38.33861 | -87.345 | 449 | 2623 |
| Oakland City Junction | city | Indiana | United States | 38.33167 | -87.30139 | 426 | 2636 |
| Oaklandon | city | Indiana | United States | 39.87278 | -85.95694 | 797 | 29276 |
| Oakley | city | Indiana | United States | 40.70194 | -86.0125 | 790 | 3566 |
| Oaktown | city | Indiana | United States | 38.87111 | -87.44139 | 479 | 2111 |
| Oakville | city | Indiana | United States | 40.07917 | -85.39056 | 997 | 3484 |
| Oakwood | city | Indiana | United States | 41.67833 | -86.78639 | 764 | 9539 |
| Oakwood | city | Indiana | United States | 41.54972 | -84.91361 | 898 | 2181 |
| Oakwood Park | city | Indiana | United States | 41.41139 | -85.73833 | 869 | 8266 |
| Oatsville | city | Indiana | United States | 38.40694 | -87.4075 | 439 | 1862 |
| Ober | city | Indiana | United States | 41.27083 | -86.52444 | 731 | 2163 |
| Occident | city | Indiana | United States | 39.69111 | -85.47833 | 964 | 2258 |
| Ockley | city | Indiana | United States | 40.48833 | -86.63389 | 688 | 1837 |
| Octagon | city | Indiana | United States | 40.52639 | -86.99222 | 780 | 5846 |
| Odell | city | Indiana | United States | 40.28778 | -87.07417 | 748 | 1497 |
| Odon | city | Indiana | United States | 38.84278 | -86.99139 | 534 | 2253 |
| Ogden | city | Indiana | United States | 39.79917 | -85.46889 | 997 | 3304 |
| Ogden Dunes | city | Indiana | United States | 41.62278 | -87.19167 | 646 | 37341 |
| Ogilville | city | Indiana | United States | 39.12583 | -86.01528 | 659 | 4635 |
| Old Adamsboro | city | Indiana | United States | 40.78333 | -86.26111 | 695 | 6010 |
| Old Bargersville | city | Indiana | United States | 39.5175 | -86.15583 | 849 | 8868 |
| Old Bath | city | Indiana | United States | 39.50833 | -84.89167 | 997 | 1713 |
| Old Halfway | city | Indiana | United States | 40.49056 | -87.06583 | 698 | 2342 |
| Old Hill | city | Indiana | United States | 39.30194 | -87.2075 | 544 | 1664 |
| Old Milan | city | Indiana | United States | 39.14639 | -85.1325 | 997 | 3362 |
| Old Pekin | city | Indiana | United States | 38.49722 | -86.00333 | 698 | 2829 |
| Old Saint Louis | city | Indiana | United States | 39.32056 | -85.78556 | 698 | 3514 |
| Old Tip Town | city | Indiana | United States | 41.22361 | -86.11528 | 774 | 2301 |
| Old Town | city | Indiana | United States | 40.25806 | -87.38667 | 672 | 855 |
| Oldenburg | city | Indiana | United States | 39.33972 | -85.20444 | 898 | 2703 |
| Oldtown | city | Indiana | United States | 39.09472 | -84.84694 | 495 | 14541 |
| Olean | city | Indiana | United States | 38.99028 | -85.21861 | 918 | 2049 |
| Olin | city | Indiana | United States | 40.14917 | -87.43056 | 551 | 1972 |
| Olio | city | Indiana | United States | 39.97139 | -85.92111 | 797 | 9616 |
| Olive | city | Indiana | United States | 41.7 | -86.44806 | 734 | 4184 |
| Oliver | city | Indiana | United States | 38.04333 | -87.83917 | 390 | 1959 |
| Omega | city | Indiana | United States | 40.19833 | -85.93917 | 846 | 2782 |
| Ontario | city | Indiana | United States | 41.70222 | -85.3825 | 895 | 4266 |
| Onward | city | Indiana | United States | 40.69472 | -86.195 | 770 | 5236 |
| Oolitic | city | Indiana | United States | 38.90083 | -86.52528 | 488 | 11518 |
| Ora | city | Indiana | United States | 41.17389 | -86.55306 | 711 | 1922 |
| Orange | city | Indiana | United States | 39.58417 | -85.29917 | 1076 | 1487 |
| Orangeville | city | Indiana | United States | 38.63139 | -86.55667 | 662 | 1460 |
| Orangeville | city | Indiana | United States | 41.33583 | -84.85694 | 797 | 3013 |
| Orchard Grove | city | Indiana | United States | 41.28972 | -87.35361 | 679 | 4029 |
| Orchard Heights Addition | city | Indiana | United States | 41.60167 | -86.23972 | 849 | 48537 |
| Orchard Highlands | city | Indiana | United States | 41.68278 | -86.83583 | 649 | 34826 |
| Orchard Park | city | Indiana | United States | 39.9375 | -86.13 | 810 | 73161 |
| Orestes | city | Indiana | United States | 40.26944 | -85.72806 | 846 | 8849 |
| Organ Springs | city | Indiana | United States | 38.47667 | -86.16472 | 738 | 2335 |
| Oriole | city | Indiana | United States | 38.16889 | -86.50472 | 741 | 871 |
| Orland | city | Indiana | United States | 41.73056 | -85.17167 | 948 | 2413 |
| Orleans | city | Indiana | United States | 38.66167 | -86.45167 | 695 | 2719 |
| Ormas | city | Indiana | United States | 41.295 | -85.54611 | 898 | 2855 |
| Orrville | city | Indiana | United States | 38.45806 | -87.68611 | 429 | 2674 |
| Osborn | city | Indiana | United States | 41.5925 | -87.46889 | 600 | 144426 |
| Osborn Landing | city | Indiana | United States | 41.28111 | -85.79694 | 846 | 17216 |
| Osceola | city | Indiana | United States | 41.665 | -86.07583 | 725 | 23128 |
| Osgood | city | Indiana | United States | 39.12917 | -85.29167 | 997 | 2395 |
| Ossian | city | Indiana | United States | 40.88056 | -85.16639 | 797 | 4693 |
| Oswego | city | Indiana | United States | 41.32028 | -85.78722 | 846 | 8078 |
| Otis | city | Indiana | United States | 41.59917 | -86.90583 | 754 | 7289 |
| Otisco | city | Indiana | United States | 38.54222 | -85.66722 | 600 | 3692 |
| Otsego Center | city | Indiana | United States | 41.5725 | -84.90889 | 954 | 2181 |
| Otter Creek Junction | city | Indiana | United States | 39.54639 | -87.34833 | 508 | 10845 |
| Otter Village | city | Indiana | United States | 39.11861 | -85.33139 | 997 | 2117 |
| Otterbein | city | Indiana | United States | 40.49056 | -87.09639 | 715 | 1768 |
| Otto | city | Indiana | United States | 38.57083 | -85.46694 | 728 | 1852 |
| Otwell | city | Indiana | United States | 38.45472 | -87.09222 | 498 | 1235 |
| Owasco | city | Indiana | United States | 40.46083 | -86.62806 | 708 | 1837 |
| Owen | city | Indiana | United States | 38.45806 | -85.54194 | 603 | 7455 |
| Owensburg | city | Indiana | United States | 38.92306 | -86.72972 | 702 | 1880 |
| Owensville | city | Indiana | United States | 38.27194 | -87.68778 | 521 | 1443 |
| Oxford | city | Indiana | United States | 40.51972 | -87.24778 | 741 | 1166 |
|
|